The energy an animal must expend to move uphill is

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The energy an animal must expend to move uphill is proportional to its body weight, whereas the animal’s energy output available to perform this task is proportional to its surface area. This is the reason that small animals, like squirrel, can run up a tree trunk almost as fast as they can move on level ground, whereas large animals tend to slow down when they are moving uphill.

Which one of the following is an assumption on which the explanation above depends?

(A) The amount of energy needed to move uphill is no greater for large animals that it is for small animals.
(B) Small animals can move more rapidly than large animals can.
(C) The ratio of surface area to body weight is smaller in large animals than it is in small animals.
(D) There is little variation in the ratio of energy output to body weight among animals.
(E) The amount of energy needed to run at a given speed is proportional to the surface area of the running animal.

Please provide the reasoning.

I answered the question using ratio:
let ratio for large animals = S/E
Ratio for small animals = s/e
option C: S/E < s/e.........when inverted looks like this:
E/S > e/s........ that is:
energy expended per unit space (for large animals) > that for small animals...
tallies with the stimulus and is thus the CORRECT answer.

let ratio for large animals = S/E
Ratio for small animals = s/e
option C: S/E < s/e.........when inverted looks like this:
E/S > e/s........ that is:
energy expended per unit space (for large animals) > that for small animals...
tallies with the stimulus

thats the kind of representation i was looking for , Got C in
3:00 min

tough question..i think its btwn B and C, leaning towards B

IMO C

The energy an animal must expend to move uphill is proportional to its body weight, whereas the animal’s energy output available to perform this task is proportional to its surface area. This is the reason that small animals, like squirrel, can run up a tree trunk almost as fast as they can move on level ground, whereas large animals tend to slow down when they are moving uphill.
Which one of the following is an assumption on which the explanation above depends?
(A) The amount of energy needed to move uphill is no greater for large animals that it is for small animals --> counterfact
(B) Small animals can move more rapidly than large animals can --> it's not about the speed of large animals to small animals, it's about speed of each in uphill in compared with each' speed in flat ground
(C) The ratio of surface area to body weight is smaller in large animals than it is in small animals -->the best. Because such ratio of large animals is not equal to that of small animals, large animals can;t remain its speed when moving uphill as can small animals when moving uphill
(D) There is little variation in the ratio of energy output to body weight among animals --> no influence
(E) The amount of energy needed to run at a given speed is proportional to the surface area of the running animal -->not qualified enough to be basis of the argument

Why B ?

IMO c shud be answer.. as the per logic above..

I'll go with C.

I also vote for C.

B is out, since in the argument its mentioned that :


We don't have any comparison of how these animals perform on level ground. The comparison is only for uphill.

Straightaway C..

Answer can be prephased before even seeing the choices.

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(1:10)

Im just skeptical about C because it could be that the surface/body ratio could be bigger on smaller animals. You could assume either way

Thanks Minheequang . OA is C

The answer is ofcourse.....But I o see one more flaw in the argument...While talking about the energy required and available, the direction goes to the speed....Which lead me to E initially..Can someone pls explain why E will not be credible...

I will also go with C for same reason....

it should be C

IMO C.

@gmatbull,

You must have done good DS

Guessed C... but really tough one.. mine was a pure lucky guess

answer is C

good question and good explanation by gmatbull

should be c

i will go with c