Why?
Because most amphibian species populations vary greatly from year to year due to natural weather variations.
The author also assumes that the certain amphibian populations we’re talking about are among the “most” species whose populations are known to vary greatly due to weather variation.
A
The amphibian species whose population declines have been attributed by many scientists to industrial pollution are not known to be among those species whose populations do not vary greatly as a result of natural variations in the weather.
B
The variations in amphibian species’ populations that result from natural variations in the weather are not always as large as the amphibian population declines that scientists have attributed to industrial pollution.
C
Either industrial pollution or natural variations in the weather, but not both, caused the amphibian population declines that scientists have attributed to industrial pollution.
D
If industrial pollution were reduced, the decline in certain amphibian populations would be reversed, and if industrial pollution increases, the decline in certain amphibian populations will be exacerbated.
E
If industrial pollution is severe, it can create more variations in the weather than would occur naturally.
Columnist: On average, about 70 percent of the profit from tourism in developing countries goes to foreign owners of tourist businesses. In general, as a country becomes a more established tourist destination, the proportion of revenues exported in this way increases. However, tourists can counteract this effect by obtaining accommodations and other services directly from local people.
Summary
Columnist: On average, 70% of tourism profits in developing countries go to foreign business owners. As a country becomes a more popular tourist spot, this percentage tends to rise. However, tourists can counteract this effect by getting accommodations and other services directly from locals.
Strongly Supported Conclusions
In at least some situations, tourists are able to influence local economies.
In some developing countries that are established tourist destinations, most tourism profits go to foreign owners of tourist businesses.
A
Tourists in a developing nation should obtain accommodations and other services directly from local people if most of the profits from tourism in that nation go to foreign owners of tourist businesses.
Unsupported. The stimulus tells us that tourists can counteract the profits of foreign business owners by obtaining services from local people, but it does not provide a value judgement as to what tourists should or should not do.
B
In at least some of the developing countries that are most established as tourist destinations, most of the profits from tourism go to foreign owners of tourist businesses.
Strongly supported. An average of 70% of tourism profits go to foreign business owners. This increases when a country is a more established tourism spot. So, in some of the developing countries that are most established as tourist spots, most tourism profits go to those owners.
C
In at least some developing countries, tourists obtain most of their accommodations and other services directly from local people.
Unsupported. The stimulus tells us that tourists can obtain accommodations directly from local people, but we do not know whether tourists actually obtain these things from local people in any developing countries.
D
In general, as a developing country becomes a more established tourist destination, local people become progressively poorer.
Unsupported. The stimulus tells us that a large percentage of tourism profits are exported, but there is also a percentage that remains in the country. We do not know that local people become progressively poorer as tourism becomes more established.
E
Tourists who obtain accommodations and other services directly from local people do not contribute in any way to the profits of foreign owners of tourist businesses.
Unsupported. Tourists who obtain accommodations and other services directly from local people may help to counteract the rising profits of foreign business owners, but we do not have enough information to conclude that they do not contribute in any way to those profits.