Critical Reasoning

Capuchin monkeys in Venezuela often rub a certain type of millipede into their fur. Secretions of these millipedes have been shown to contain two chemicals that are potent mosquito repellents, and mosquitoes carry parasites that debilitate the capuchins. The rubbing behavior is rare except during the rainy season, when mosquito populations are at their peak. Therefore monkeys probably rub millipedes into their fur only because doing so helps protect them against mosquitoes.

Which of the following would be most useful to determine in order to evaluate the argument?


(A) Whether the two chemicals provide any protection for millipedes against their own predators

(B) Whether the type of millipede used by the capuchin monkeys in Venezuela is found in other parts of the world

(C) Whether animals other than capuchins rub insects of any kind into their fur

(D) Whether the only time millipedes are readily available to capuchins is during rainy season

(E) Whether secretions of any other insects accessible to capuchins contain chemicals that repel the mosquitoes


OA D

Source: GMAT Prep