let us simplify what the question says -
Energy required = constant * body weight
Energy output = constant * surface area.
Now, (energy output) / (energy required) = constant * (surface area) / (body weight)
We are told that smaller mammals can run almost as fast as they can on ground, whereas large mammals tend to slow down.
this means that energy output is more than able to meet the energy required in smaller mammals (that is why they do not slow down).
Whereas it is less in larger mammals (they slow down because they are not able to meet energy requirements)
Hence, ratio > 1 (in larger mammals) and < 1 (in smaller mammals). If we compare the two ratios, we get -
(surface area)/ (body weight) [for small mammals] > (surface area)/ (body weight) [for large mammals]
Which option states this? Option C.
A - Incorrect.
Not true. We know that they require more energy as their body weight is more.
B - Incorrect.
We do not know whether they can actually run at higher speeds than larger mammals. All we know is that they do not slow when moving uphill but larger mammals do.
We do not have any idea about their actual speeds.
Moreover, we have data only when they move uphill. Other scenarios are not known.
D - Incorrect.
We know that (energy output/surface area) is constant. We don't have any idea about (energy output/ body weight).
E - Incorrect.
Energy required is proportional to the body weight. We cannot infer about surface area.
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