PT 1.S3.Q21 - Necessary assumption question

asb227-1-1-1-1

Is anyone able to explain this question to me? I am horrible with proportions/math/etc, and I don't understand why my answer was wrong or why the right one is right. Thank you!!

Help

TomvsLSAT

First time posting an explanation, bare with me if my thought process is a little off.
Since this is a NA question, the correct answer in negated form would ruin the stimulus and it wouldn't make sense.

So, I see the word MUST, which is a necessary indicator.

First sentence split into two
The energy spent to move uphill MUST be proportional to body weight
The energy available MUST be proportional to the surface area.

Second sentence split into two
Given that the output is proportional to its surface area, squirrels can run faster.
BUT given that the output is proportional to its surface area, elephants run slower.

Energy spent uphill = body weight
Energy available = surface area

Intuitively, as playing with the language in the stimulus, if a squirrel is racing an elephant 100 meters, the elephant would be gasping for air as it SPENT SO MUCH ENERGY.
The squirrel would still be zooming because it HAS SO MUCH ENERGY TO SPEND

Thus, C tells us that ratio of SA to BW is smaller in large animals compared to small.

Large animal:
Energy spent uphill (1000) = body weight (1000)
Energy available (500) = surface area (500)
Small animal:
Energy spent uphill (5) = body weight (5)
Energy available (20) = surface area (20)

SA to BW
Large animal = .5.
is less than
Small animal = 4

The 'math terms' might throw you off, but read in-between the lines compared to taking every word/sentence as literal; The lsat writers will purposely have you think only narrowed down to the scope of what's said in the stimulus, but they will never give you a non-understandable term as every single test taker who either didn't major in math or had trouble in math growing up would complain that there was an unfair advantage. Always read the stimulus (for future NA questions) and reaallyyyy dive into the stimulus by finding out what piece of relevant information is missing.
Hope this helped!!!

TomvsLSAT

Oops, I forgot to add
If you negate the answer choice (C), you'll be able to see that it reads "The ratio of SA to BW is NOT smaller in large animals than small animals."

If you applied the negated answer (C) to the stimulus, then you would be able to eliminate the argument/conclusion/relationship of what allows (lower SA to BW) for small animals to run quicker; Thus, the argument is ruined.

The answer negated to nec questions will ruin the stimulus/argument!!