Sloths have less muscle than other mammals their size in order to
a. conserve energy
b. maintain a lower body weight
c. digest their food faster
d. maintain a higher body temperature

The correct answer for the blank is-

a. conserve energy.

Sloths are considered as arboreal mammals *( that is living on trees) and they have very less muscle mass, which is about 30 % lesser than that of similar sized mammals. This is because their muscles are made up of slow-twitch fibers, which provide them a lot of power to withstand any stress while not using a lot of energy.

Therefore, their lesser muscle mass help them in conserving energy.

the fossil record provides evidence of a common ancestor to many species.