Although an insecticide may initially prove effective in reducing mala

Fame,
I would say you are confused because this is a poorly written question. In a good GMAT CR question, it may be confusing when thinking it through, but when the OA & OE are revealed, everyone has an "aha!" and feels that it makes sense.

I tend to agree with VeritasPrepKarishma's excellent analysis above. In her view, the scientists want to kill mosquitoes but leave the inter-mosquito competition intact. If they kill the older mosquitoes, this will have the advantage of killing mosquitoes that are "essential to maintaining the life cycle of the malaria parasite" without reducing genetic competition in the mosquito population. Among other things, the question expect the non-scientist reader to know that, by the "malaria parasite", they mean the protist that cause malaria, i.e. that malaria is carried by a parasite that lives in the mosquito. I think the question demands a bit too much outside knowledge of science --- I don't think the GMAT would automatically expect the reader to know the details of how genetic competition plays out or the details of how malaria is carried or transmitted. I think it's very very easy to write a hard CR question if it involves specialized knowledge of some scientific field, knowledge that maybe folks learned at one time in high school but is not uppermost in their minds. I think it's much harder to write a CR question that treats everyday topics that are well-known to everyone, that is puzzling to many readers on first reading, but that makes complete sense to everyone once the OE is given. The GMAT does this consistently with its CR question. This particular question falls well short of that standard.

That's my 2¢

Mike

IMO E

I just have doubt on B...
Is this weakener/strengthener ???

"presence of older mosquitoes—those ten or more days old—is essential to maintaining the life cycle of the malaria parasite"-------- part of the premise. we have to strengthen the fact that:-

researchers have proposed addressing the problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.
Lets scan the options contenders B and E,

option B states that "B. The older mosquitoes have completed their breeding activity.".......If they have completed their breeding cycle, then there is no use of targeting old mosquitoes.

E. The older mosquitoes are not as susceptible to insecticides as younger mosquitoes.--------Though this is a repetition of the premise but there is no other option close to it.

If the old mosquitoes are not susceptible to insecticide than they need to be targeted for elimination and it is already stated in the premise that these older mosquitoes are needed to thrive the life cycle.

Hence i feel that E is the best option which strengthens and B is somewhat weakening the argument.

this was completely over my head. Had to go though the argument and answer choice 3-4 times to understand what is actually required to strengthen and which answer choice will do the trick.

After all the torture I will pick B.

Will love to see how others comprehend and explain.

@gmatbull : Kudos to you for such lovely question that push our limit.

B the virus transmits through the mosquito population through breeding... just a guess

I think it's E... Could u pls tell the ans

Very tough one indeed. IMHO, the answer should be E. It would make sense to research a new method for killing mosquitoes that have survived being sprayed with insecticides at a young age. On the real GMAT, I would just pick E and move on. Will not be too worried if I get this wrong. IMHO, B is wrong. If the mosquitoes have already bred, then they would have already passed on their strong genes to the offsprings hence targeting only the older mosquitoes will have very limited use.

Answer should be E.

Kudos Please... If my post helped.

Option A, and D are clearly irrelevant. Only contenders that affect the proposal are B,C and E.
Now B, if anything, weakens the proposal. if breeding activity is completed that means older mosquitoes have passed on the resistance. Eliminate B.
C and E remains. We can also check that from passage it is clear that older mosquitores have better resistance to insecticide. and if choice E says the same thing- it means it is just restating the premise cleverly so that it will be picked. Eliminate E.
Choice C remains. Now notice, older mosquitoes are 10 or more days old. If new approach requires frequent application of pesticides that would mean mosquitoes will not get chance to get older or basically presence of old mosquitoes will be highly unlikely, thus success of researchers' plan is ensured.

Ans C it is!

No doubt the question is a tough one even with the splits:
B(2); C(1); and E(5). I also went with E, but that was not to be...

Thanks everyone for your contributions, OA is however, .

By focusing on , how would researchers achieve their aim?

Haha... Would never have gone with B any day.....

@Vineetk & Cpanagio,
what are your explanations for choosing B?

I went with B because of below highlighted statement provided in the argument:

Because the presence of older mosquitoes—those ten or more days
old—is essential to maintaining the life cycle of the malaria parasite, researchers have proposed addressing the
problem of pesticide resistance by searching for a means of targeting only older mosquitoes for elimination.

Maintenance of life cycle (reproduction) is an important activity that's why older mosquito comes in picture. The pesticide will target the older mosquito (after reproduction) but not on young ones so that young ones become 10 or more days old and reproduce and life cycle can continue. At the same time, older mosquito can be killed by this pesticide, controlling the population.

Supposing the old mosquitoes are eliminated after passing the resistant genes to the younger ones, does it make any sense?

My expectation is that u target the old ones (before breeding starts). That way, u prevent them from passing the stubborn genes
to their young ones. Otherwise, anytime u eliminate the old ones, the younger ones (in possession of the adamant genes) transfer
the genes and the vicious cycle continues...

E, on the other hand, says the adult mosquitoes are less susceptible than their younger ones. So, it becomes easier to eliminate the
re-production cycle. Also, we are guaranteed that the agent (or mechanism) for transfer of the genes-adult mosquitoes- are easily
killed, leaving only the younger but ones who grow old and also become less vulnerable to the insecticide. Malaria is thus easier to control.

Am sorry, OE not available, but What do u think Vineetk?

If I somehow come to know that I shall be facing such questions on real test, then I will surely not be taking test within a year.

Below is my inference :
In B- If we eliminate older ones before breeding, younger ones will not be produced and existing ones will also die when they become old before breeding. Thus, the mosquito population will eventually end or disappear. Life cycle will no longer continue.

In E- If old mosquito are less susceptible then danger to younger ones are more and the objective of killing only old mosquito is not achieved.

Correct me if I inferred wrongly.

@ Vineetk,

For B, yes, that's precisely how I feel it should have been worded.

E: older mosquitoes are LESS susceptible to insecticide THAN the younger ones. The older ones are more difficult to
kill with the insecticide.

If Older ones transfer immunity genes to younger ones, and are more difficult to eliminate, then any such plan that
will eliminate the older ones will assure the researchers that malaria will be curtailed.

This is my opinion....

I chose answer B.

Reasoning:

The goal is to support the goal of targeting older mosquitos in order to reduce the problem of genetic resistance to pesticides.

Answer B would support this goal - if the older mosquitos being targeted have already completed the breeding process, they will not pass along their resistance as they will not produce any additional offspring, and resistance is passed on genetically.