Publicity campaigns for endangered species are unlikely to have much impact on the most important environmental problems, for while the ease of attributing feelings to large mammals facilitates evoking sympathy for them, it is more difficult to elicit sympathy for other kinds of organisms, such as the soil microorganisms on which large ecosystems and agriculture depend. Which one of the following is an assumption on which the argument depends? (A) The most important environmental problems involve endangered species other than large mammals.

(B) Microorganisms cannot experience pain or have other feelings. (C) Publicity campaigns for the environment are the most effective when they elicit sympathy for some organism. (D) People ignore environmental problems unless they believe the problems will affect creatures with which they sympathize. (E) An organism can be environmentally significant only if it affects large ecosystems or agriculture.

People only sympathize with large mammals, and thus won't sympathize with other organisms. Thus publicity campaigns are unlikely to impact important env problems.

The assumption is clearly that the important env problems are not in fact restricted to large mammals, since if that were the case, eliciting sympathy wouldn't be a problem at all and the publicity campaigns would be likely to have an impact.

This is clearly stated in A.

As for D, while this may be tempting, remember, an assumption is essential for an argument to be true. This option seems to distort the information in the passage which clearly states, "more difficult to elicit sympathy for other organisms". So to say that people IGNORE them completely is too extreme and is not really an assumption required for the argument.

This was a tough one.

True, but felt D more critical assumption for conclusion because conclusion is "Publicity campaigns for endangered species are unlikely to have much impact on the most important environmental problems"

applying negation to D i.e. attacks conclusion, a scenario not in A.

let me know ur opinion

I see what you mean. To be honest, if the question stem was "Which of the following, if true, would most strengthen the conclusion" D would have been a contender. But you see, the question is "Which is

an assumption on which the argument DEPENDS"

The argument only depends on people being LESS likely to sympathize with smaller organisms, but D is too extreme in suggesting that it depends on people IGNORING them completely because they do NOT sympathize with them. As far as I can see, it purely depends on how extreme it is. Extreme assumptions can distort the argument by changing a moderate argument to an extreme one.

The negation test does seem to attack conclusion, but if you look closely, it actually does not. Let's negate it : People do not ignore problems for those creatures they do not sympathize with. Well this is all the more reason not to bother with Publicity campaigns, since it is clear from the argument that they are meant to elicit sympathy (in this context, we are not bothered with what real life campaigns will achieve) and choice D does not offer any other mechanism by which publicity campaigns can affect env problems. Thus, if people consider env problems irrespective of sympathy, it is all the more unlikely that publicity campaigns will have much of an impact.

In the real world you would probably argue that such campaigns would create awareness and do not particularly depend on eliciting sympathy, but don't stretch it so much for the GMAT. You have to assume the evidence in the argument as being the only facts you know of and don't bring outside info in, unless a choice in the answers leads towards it obviously.

Again, tough question, really represents some of those 800 level CR questions imo.