Humans are better adapted for running than are other primates; a narrow waist and a midsection that can turn allow us to swing our arms and prevent us from zigzagging on the trail.

A. allow us to swing our arms and prevent
B. allows us to swing our arms and prevent
C. allows us to swing our arms and prevents.
D. is what allows us to swing our arms and prevents
E. allow us to swing our arms and to prevent

Source : Manhattan Prep
OA=A