Howler Monkeys Have Smaller Brains Than Equally Sized Spider Monkeys

Multiple Choice

Howler monkeys have smaller brains than equally sized spider monkeys.This is thought to stem from the fact that:

A) howler monkeys eat more fruit than spider monkeys.
B) howler monkeys eat less fruit than spider monkeys.
C) howler monkeys eat less meat than spider monkeys.
D) howler monkeys live in larger social groups than spider monkeys.