Dengue fever is a viral infection transmitted by the Aedes mosquito

Question

Dengue fever is a viral infection transmitted by the Aedes mosquito, whereas malaria is a parasitic infection transmitted by the Anopheles mosquito. Since both types of mosquito are prevalent on Nicaragua’s “Mosquito Coast,” anyone with a compromised immune system should not travel to this region, particularly during the rainy season.

All of the following, if true, strengthen the argument EXCEPT:

(A) Medicines taken to prevent or treat malaria can cause serious health complications for people with weak immune systems.
(B) The Nicaraguan government is trying to reduce the number of mosquitoes on the Mosquito Coast.
(C) A compromised immune system has difficulty fighting either viral or parasitic infections.
(D) During the rainy season, the populations of both Aedes and Anopheles mosquitoes multiply in the Mosquito Coast.
(E) The most effective chemical insect repellent has been shown to cause brain damage upon repeated application to the skin.

Jaidude · Answer

I usually love solving EXCEPT questions but this one was kinda LAME.
The answer in my opinion is B, but I'd love to see how an expert solves this one more efficiently. bb nightblade354 GMATNinja !
" Since both types of mosquito are prevalent on Nicaragua’s “Mosquito Coast,” anyone with a compromised immune system should not travel to this region, particularly during the rainy season."
try to find 4 answers that strengthen the argument!

A, C and D are easy eliminations but B and E is an issue

I eliminated E as it goes along the same line of thinking as A. (speak of medicine/chemical )
though E says insect repellent which seems too vague of a statement. I wasn't happy picking B but I did it anyway.

IMO B

nightblade354 · Answer

Jaidude , skip Kaplan, skip the headache.

ElninoEffect · Answer

(A) Medicines taken to prevent or treat malaria can cause serious health complications for people with weak immune systems.
 Strengthner.(makes me believe on the point that I should not travel there) 
(B) The Nicaraguan government is trying to reduce the number of mosquitoes on the Mosquito Coast.
 Weakener(makes me think if that's the case there might be a chance I might go there.) 
(C) A compromised immune system has difficulty fighting either viral or parasitic infections.
 Strengthner(same reason as A) 
(D) During the rainy season, the populations of both Aedes and Anopheles mosquitoes multiply in the Mosquito Coast.
 Strengthner(same reason as A) 
(E) The most effective chemical insect repellent has been shown to cause brain damage upon repeated application to the skin.
 Strengthner(same reason as A)

kaptainklutz · Answer

The only argument weakening the proposition was that the government is taking steps and travelling might not be so bad after all hence correct answer B

durant25 · Answer

Isn't E completely off the topic/out of Scope?

guddo · Answer

Dengue fever is a viral infection transmitted by the Aedes mosquito, whereas malaria is a parasitic infection transmitted by the Anopheles mosquito. Since both types of mosquito are prevalent on Nicaragua’s “Mosquito Coast,” anyone with a compromised immune system should not travel to this region, particularly during the rainy season.
 
 All of the following, if true, strengthen the argument EXCEPT:

The argument says people with compromised immune systems should avoid the Mosquito Coast because two disease-carrying mosquitoes are common there.  So a strengthening answer should increase the medical risk of traveling there , especially for people with weak immune systems or during the  rainy season .

(A) Medicines taken to prevent or treat malaria can cause serious health complications for people with weak immune systems.

This strengthens. If even the medicine for malaria can be dangerous for such people, then travel becomes riskier.

(B) The Nicaraguan government is trying to reduce the number of mosquitoes on the Mosquito Coast.

This is correct. This does not strengthen the warning. If anything, it suggests that the mosquito problem may be reduced. Also, merely “trying” does not show that the risk is higher.

(C) A compromised immune system has difficulty fighting either viral or parasitic infections.

This strengthens. Dengue is viral and malaria is parasitic, so this directly supports the claim that people with compromised immune systems are especially at risk.

(D) During the rainy season, the populations of both Aedes and Anopheles mosquitoes multiply in the Mosquito Coast.

This strengthens. It directly supports the phrase “particularly during the rainy season.”

(E) The most effective chemical insect repellent has been shown to cause brain damage upon repeated application to the skin.

This strengthens. If the best protection has serious risks, then travel is even less advisable.

Answer: (B)

AllisonBell · Answer

Great question! It can certainly seem that way, and it’s actually pretty common for strengtheners to appear off topic or out of scope at first glance. That’s because one of the best ways to strengthen an argument is to anticipate an objection  that hasn’t yet been raised.

This argument’s conclusion is that  anyone with a compromised immune system should not travel to this region.  Answer choice E anticipates an objection: couldn’t people with a compromised immune system travel safely if they took effective precautions against being bitten by mosquitos?

Answer choice E rules out that possible objection by pointing out a serious issue with the best possible chemical repellant. Since people can’t safely apply this repeatedly without risking brain damage, it’s not a viable way to prevent mosquito bites. And the fewer safe, effective ways available to prevent mosquito bites, the stronger the argument that people with compromised immune systems shouldn’t risk the exposure.

For a great intro to Critical Reasoning, check out ManhattanPrep’s   Free GMAT Trial Classes  . Session one includes a deep dive into the foundations of CR!

Best,

egmat · Answer

Hi durant25,

I get why E  feels  off-topic: it talks about insect repellent, not the diseases or the mosquitoes directly. But in CR, "in scope" isn't about matching the topic words - it's about whether the choice  acts on the argument's conclusion . And here it does.

Track the conclusion first.  The author says anyone with a weak immune system  should not travel  to the Mosquito Coast. The unstated counter-move to that advice is obvious:  "Why avoid the place - can't I just protect myself instead?"  The strongest protection would be a good insect repellent.

Now read E in that light: 
 "The most effective chemical insect repellent has been shown to cause brain damage upon repeated application to the skin."

This shuts the door on the most natural alternative to staying away. If even the  best  repellent is dangerous to use, then "just protect yourself and go" stops being a safe option - so  not traveling  looks wiser. That directly supports the conclusion, which is exactly what a strengthener does. So E is  in  scope.

Notice this is the same machinery as A and E both: A removes "just take the medicine" as a safe out, and E removes "just use repellent" as a safe out. Both push you toward avoidance.

Compare that with  B  - the government reducing mosquitoes makes the region  safer , which pushes against the advice to avoid it. That's why B is the EXCEPT answer, not E.

Quick gut-check for "is this out of scope?":  don't ask  "does it share the topic?"  - ask  "does it make the conclusion more or less likely?"

- If E said the best repellent is  cheap and harmless , would that help or hurt the "don't travel" advice?
- See how flipping that one fact flips the effect? That's the test for relevance - not the topic label.

Answer: B

Dengue fever is a viral infection transmitted by the Aedes mosquito

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Dengue fever is a viral infection transmitted by the Aedes mosquito

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards