The correct answer is D. Longer legs in relation to arms
Explanation:
In biology, the term "biped" is used to refer to animals that move using two limbs or extremities, this includes human beings. On the other hand, knuckle walkers move using their two rear limbs and their front knuckles, this is the case of gorillas.
This type of locomotion also lead to different physical structures, for example, knuckle walkers often have a more curved spine; also, in knuckle walkers the legs and arms are of similar lengths as the animal needs to move in the four limbs, but in the case of bipeds the legs are longer and often more developed or stronger as all the weight of the body is held by the legs and thus, arms tend to be shorter. Thus, bipeds have longer legs in relation to arms in comparison to knuckle walkers.
