Capuchin monkeys in Venezuela often rub a certain type of

Question

Capuchin monkeys in Venezuela often rub a certain type of millepede 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 heps 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 repellents.
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.

deowl · Answer

D it is

biggamejames · Answer

Yup, D.

XxxyyY · Answer

one more for D

giddi77 · Answer

Guys.. Why isn't it E?

buzzgaurav · Answer

I was also inclined towards E but on closer look D was right.
In E, it states 'any other insect'. If it is known that millepede repel insects then we don't need to test any other insect for the same effect.

Whereas in D, if we can determine the availability of millepede in other seasons then we can compare and say clearly that although millepedes are available throughout the year yet capuchin monkeys use them more during rainy season to repel mosquitoes.

ps_dahiya · Answer

D it is.

IMO E is out of scope. We are not concerned about any other insect.

giddi77 · Answer

Thanks Gaurav and PSD!

There are 2 things to evaluate:
1. The rarity of Monkeys' behavior - Why it is displayed only during a certain season.
2. The behavior itself - Why that use only millipedes? It could be for other reasons than mosquito bites.

To evaluate #1 - We defenitely need to know if the behavior is rare because of the avalibility of millipedes happens to be only during a certain season or all throught the year. --> Defeitely D is the answer
To evaluate #2 - We need to show that it is not the millipedes that are important. If there were other insects with such chemicals the monkeys could use them instead. --> May be E is the answer.

May be I am reading too much into this silly question... If GMATPrep says D, I'll take it.

ps_dahiya · Answer

May be you are right but I think you are thinking too far and leaving the argument behind.

gmatmba · Answer

D..

wlee76 · Answer

This is probably a late reply, but I was doing this question on the gmatprep and also picked E.

Upon reading this post, and thinking about it a bit more, D is correct i think because 
- We need to know if the monkeys rub these millipedes at any other time of the year. If they did, we can suspect that they might do it for another reason other than the mosquitos.

Although slight doubt does remain as to why it is worded "readily avaliable"

rbcola · Answer

Must be the spinach I ate last night.

kripalkavi · Answer

One more for  D . I actually narrowed it down to B and D. 

E can be eliminated as it is out of scope. 

conclusion says:  monkeys probably rub millipedes into their fur only because doing so heps protect them against mosquitoes. 

We need to focus on  millipedes , not  other insects .Although answering E will provide a valuable insight,   on the GMAT   it is out of scope.

tennis1ball · Answer

D 2

Capuchin monkeys in Venezuela often rub a certain type of

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