A plausible explanation of the disappearance of the dinosaurs is what is known as the comet theory. A large enough comet colliding with Earth could have caused a cloud of dust that enshrouded the planet and cooled the climate long enough to result in the dinosaurs’ demise.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the comet theory is a plausible explanation of the dinosaurs’ extinction. This is based on the idea that a collision of a large enough comet into the Earth could have caused a dust cloud that could have cooled the climate long enough to cause the extinction of the dinosaurs.

Notable Assumptions
The author assumes that a large enough comet existed and could have collided with Earth at the time in question. He also assumes that the impact would cause a dust cloud that would cover the planet, and that this would cool the climate long enough to lead to the dinosaurs’ extinction. (The author says that these events “could” happen––we don’t know their likelihood. It could be a very slim possibility.) The author assumes that, even if these events occurred, the cooling caused by the comet is what led to the dinosaurs’ extinction.

A
One of the various schools of paleontology adheres to an explanation for the disappearance of the dinosaurs that is significantly different from the comet theory.
The author is only arguing that the comet theory is plausible; the fact that other theories differ from the comet theory doesn’t weaken the argument. It doesn’t weaken our argument that other plausible explanations may exist.
B
Various species of animals from the same era as the dinosaurs and similar to them in physiology and habitat did not become extinct when the dinosaurs did.
(B) suggests that the extinction of the dinosaurs was driven by some factor that differentiated dinosaurs from other animals with similar habitat and climate needs. If the comet theory was true, animals with similar physiology and habitat to dinosaurs would have gone extinct too.
C
It cannot be determined from a study of dinosaur skeletons whether the animals died from the effects of a dust cloud.
(C) just says that one specific kind of evidence cannot be used. The inability to use skeletons as evidence does not weaken the argument that the comet theory is plausible. (C) makes the inappropriate assumption that skeletons are the only source of information available.
D
Many other animal species from the era of the dinosaurs did not become extinct at the same time the dinosaurs did.
(D) is too broad. The animal species referenced in (D) could have had vastly different requirements for habitat and climate. It makes sense that some animals survived the incident that killed the dinosaurs.
E
The consequences for vegetation and animals of a comet colliding with Earth are not fully understood.
The argument that the comet theory is plausible doesn’t require a full understanding of the impacts of a comet collision on plants and animals, so (E) does not impact the argument.

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Party spokesperson: The opposition party’s proposal to stimulate economic activity in the province by refunding $600 million in provincial taxes to taxpayers, who could be expected to spend the money, envisions an illusory benefit. Since the province’s budget is required to be in balance, either new taxes would be needed to make up the shortfall, in which case the purpose of the refund would be defeated, or else workers for the province would be dismissed. So either the province’s taxpayers or its workers, who are also residents of the province, will have the $600 million to spend, but there can be no resulting net increase in spending to stimulate the province’s economy.

Summarize Argument
The author’s main conclusion is that the proposal to stimulate economic activity in the province by refunding $600 million won’t actually benefit the province’s taxpayers. This is because the province’s budget is required to be in balance, which the author believes implies that the province will need to issue new taxes or fire workers in order to make up for the $600 million that would be going back to taxpayers.

Notable Assumptions
The author assumes that in order to balance the budget, the province must issue new taxes or fire workers.

A
taxpayers of the province would spend outside the province at least $300 million of any $600 million refunded to them
If taxpayers spend the refund out of province, that’s less money that would be spent on economic activity in the province. This supports the author’s point that the proposal won’t result in a net increase in spending in the province.
B
taxpayers of the province would receive any refund in partial payments during the year rather than in a lump sum
Whether the refund is in one lump sum or multiple payments doesn’t change the overall amount of the refund or whether the need to balance the budget necessitates new taxes or firing workers.
C
province could assess new taxes in a way that would avoid angering taxpayers
The taxpayers’ emotions have no clear impact on this argument. The author’s reasoning relates to the need to balance the budget and recoup the $600 million being refunded.
D
province could, instead of refunding the money, stimulate its economy by redirecting its spending to use the $600 million for construction projects creating jobs around the province
This answer describes a solution that doesn’t involve refunding $600 million to taxpayers. But the conclusion is about the refund and whether it will achieve its goal. Pointing out that we can do something besides a refund doesn’t undermine the author’s point.
E
province could keep its workers and use them more effectively, with a resulting savings of $600 million in its out-of-province expenditures
This points out how the need to balance the budget doesn’t require new taxes or firing workers. If we could keep workers and recoup $600 million by saving on out-of-province expenditures, then we don’t need to tax the province’s taxpayers or fire workers.

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