On their way from their nest to a food source, ants of most species le

Question

On their way from their nest to a food source, ants of most species leave a trail of chemicals called pheromones. The ants use the scent of the pheromones to guide themselves between the food and their nest. All pheromones evaporate without a trace almost immediately when temperatures rise above 45 degrees Celsius (113 degree Fahrenheit), as is typical during afternoons in places such as the Sahara Desert.

The statements above, if true, most strongly support which one of the following?

(A) Most ants forage for food either only in the morning or only during the night.

(B) Most ants that do not use pheromones to mark the paths they take between their nest and food live in the Sahara Desert.

(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.

(D) If any ants do not use pheromones to navigate between food and their nest, those ants use a different substance that does not evaporate in temperatures above 45 degrees Celsius.

(E) If any Saharan ants forage for food in the afternoon, those ants forage for food less efficiently when temperatures are above 45 degrees Celsius than they do when temperatures are lower.

haas_mba07 · Accepted Answer

(A) Most ants forage for food either only in the morning or only during the night.

 Out of scope. Stem says nothing about other foraging times... 

(B) Most ants that do not use pheromones to mark the paths they take between their nest and food live in the Sahara Desert.
 Again out of scope... nothing about where ants live... 

(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.
 
Correct... within the boundaries of the stem, and draws on information in the stem. 

(D) If any ants do not use pheromones to navigate between food and their nest, those ants use a different substance that does not evaporate in temperatures above 45 degrees Celsius.
 Focussing on 45 degrees temp, not the focus of the stem. 

(E) If any Saharan ants forage for food in the afternoon, those ants forage for food less efficiently when temperatures are above 45 degrees Celsius than they do when temperatures are lower.
 No mention of efficiency in stem...

sangarelli · Answer

(C ) looks good to me.The ants cannot use pheromones in general if they forage in the afternoons.

Swagatalakshmi · Answer

I'm not convinced with (C). The question stem doesn't suggest that Sahara ants operate at the same efficiency when temp is below or above 45 degrees. We are assuming that there must be some kind of natural adaptation working for these ants and therefore they use some other kind of chemical. I'll pick E and wait for OA

gmatcrook · Answer

OA is C... E needs evidence to backup the claim of efficiency.

sumitsarkar82 · Answer

I wouldn't say an Easy C... but a C nevertheless...

amit2k9 · Answer

tough call between C and E. Both leave a little element not being discussed in the argument.

gijoedude · Answer

I will go with C. Took a full 1:35. The rest of the options are out of scope or make too strong of a statement.

mourinhogmat1 · Answer

(C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.

(E) If any  Saharan ants  forage for food in the afternoon, those ants forage for food less efficiently when temperatures are above 45 degrees Celsius than they do when temperatures are lower.

I am going with C here because in E the scope is narrowed to Saharan ants rather than ants.

MBAhereIcome · Answer

premise: ants of MOST species use pheromones.
okay so there are some species that do not use pheromones.

e) use of 'ANY saharan ants' is too strong. incorrect.
c) correct.

OptimusPrimea1 · Answer

Was confused between C & E.Selected E.. But i agree with C with the explanations given above..

fieldsrd · Answer

Good catch. That makes a huge difference.

siddharthmuzumdar · Answer

Nice question. Tricky options C and E.

Went for E but realized that C makes more sense. Thanks for the explanations guys.

neha2785 · Answer

C for me also 
A ) We need pattern of sahara.
B ) possible but stating more then question 
C ) yes everything is right in premise and strengthen the argument.
D ) out of context.
E ) possibel yes, but it says “any Saharan ant” implying that it talks about all the ant, but question says “most of the ant species” which means not all

acdbe2003 · Answer

I consider between choice C and E.
But choice e need more assumption
Clearly C wins

shankar245 · Answer

C) If any ants live in the Sahara Desert and forage for food at no time but in the afternoon, those ants generally do not use pheromones to guide themselves between food and their nest.

But would this not mean that every day or every after noon the temperatur is going to be >45 degrees?

The stem says typically 45 degrees ,so is it not just an average?How can we b sure that the temperature is going to be high?

Priyanka2018 · Answer

E is wrong because in the argument it is mentioned ants go from their nest to food source and leave a chemical while going from nest to food( between nest and food) 
Nest---------------------------->food
while coming back they use the smell of the chemicals they left  (between food and nest)
 
Food------------------------->nest
E is saying they forage less efficiently for food when temperature is high , but argument is actually they are able to forage but just that going back to nest becomes difficult because the chemical, which guide them to nest ,gets evaporated.
Nothing about their efficiency to forage becomes less is mentioned in the passage
We can infer that as the chemical is evaporated above 45 degree , they do not use chemical to guide themselves as mentioned in C

Pankaj0901 · Answer

I have exactly the same doubt for option C. Are we not assuming that ants are adapting to the environment by not secreting pheromones? I am not able to understand why is C correct. I broke my head and still helpless.
Request someone to please help.

akt715 · Answer

what is difference between D and C??

tkorzhan18 · Answer

GMATNinja , why ants that don't use pheromones should be in scope in this argument? 
(I did not select C because I assumed ants should always use pheromones on their way from nest to food source. As a result of bringing additional info that Ants don't use pheromones, we are contradicting evidence noted in the argument. )

On their way from their nest to a food source, ants of most species le

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On their way from their nest to a food source, ants of most species le

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