So, in this one, the government makes the claim: "Most forests in Canada are not being damaged by acid rain.”
Then the environmentalist are up in arms, and want the conclusion changed to: "Most forests in Canada do not show visible symptoms
of damage by acid rain, such as abnormal loss of leaves, slower rates of growth, or higher mortality.”
If person A says, "X does not exist here," and person B counters by saying, "it's hard to see the visible effects of X," then essentially, person B is telling A: "You're wrong; X is really happening, but you can't see it." That is the crux of the the argument of the folks who want to change the conclusion of the report.
Choice (B) is the answer choice that directly address this.
Choice (A) = Not big news. The report said "Most
forests . . . are not being damaged," which implies that: some, at least a few, are.
Choice (C) = other countries --- off-topic
Choice (D) = Not earthshattering. Acid rain is happening --- if it weren't, they wouldn't do the report in the first place. The fact that acid rain has been happening to all forest for 15 year is probably agreed upon by all parties. The question is: is it causing damage? That's the controversial issue, which this choice doesn't address.
Choice (E) = Again, like (A), not big news. The report says, "Most
forest . . . are not being damaged," which means some are, which means the severity of damage differs from forest to forest. Anything that is already consistent with what's in the report is not going to strengthen an argument attacking it.
Does that make sense? Let me know if you have any questions.
Magoosh Test Prep