Self-study
In 1980 there was growing concern that the protective ozone layer over the Antarctic might be decreasing and thereby allowing so much harmful ultraviolet radiation to reach the Earth that polar marine life would be damaged. ████ ██████████ █████████ █████████ █████ █████████ █████ ██████████ █████████ ████ ██████ ███████████ █████ ██████ ████████ █████████
Structure: Counter-Argument
The government officials in 1980 rejected the concern that the ozone layer over the Antarctic might be decreasing and allowing damage to occur from ultraviolet radiation. They did this based on statistics that said global atmospheric ozone levels were remaining constant.
Analysis: Weaken
Notice that there's a pretty significant part vs. whole flaw in the government officials' reasoning. Just because global atmospheric ozone levels are remaining constant doesn't mean that the ozone layer in one particular area, like the Antarctic, is not decreasing. It might be decreasing and offset by increases in ozone in other parts of the world.
So it would significantly undermine the government officials' argument if we knew, for example, that other parts of the world were seeing increases in their local ozone levels, which would mean that there were decreases in other parts of the world, potentially including the Antarctic.
14.
The relevance of the evidence █████ ██ ███ ██████████ █████████ ██ ███████ ██ █████ ████████ █████ ██ ████ █████████ ██████████ ██ ██ ████ ████ ████
a
most species of █████ ███ ██████ ████ ████████ ██ ████ ████████ ██████ ████ ██ ███ █████ ███████
Irrelevant. We're trying to undermine the relevance of the government officials' evidence, which is about ozone levels, not about where most species of plant and animal life flourish.
b
decreases in the ██████ ██ ███████████ █████ ████ ███ █████████ ███ ███ ████ ██ ██ ████████ ██████ ████ ████████
Incorrect. We want an answer choice that suggests that even though global ozone levels were staying constant, ozone levels over the Antarctic were potentially seeing a dangerous decrease. (B) doesn't do that. In fact, it suggests that the ozone decrease over the Antarctic, if any, was just a seasonal phenomenon that would come back to normal. This doesn't do anything to undermine the relevance of the government officials' evidence that global ozone levels were staying constant.
c
decreases in the ██████ ██ ███████████ █████ ████ ██ ██████ ███████ ██████ ████
Irrelevant. Whether or not people were concerned about ozone levels before 1980 has no bearing on whether ozone levels above the Antarctic were actually decreasing in 1980.
d
quantities of atmospheric █████ ███████ ████ ████ ███ █████ █████ ███████████████ ██████████ █████ ██████ ██ █████ ███████
Correct. If this is true, then the government officials' evidence that global ozone levels were remaining constant fails to show that ozone levels over the Antarctic were not decreasing.
e
even where the ██████ ██ ███████████ █████ ██ ███████ ████ ███████████ █████ ███████ ███ █████████ ███████
Irrelevant. We want to undermine the relevance of the government officials' evidence, which is about ozone levels, not about ultraviolet light.