Aspotter stands near the lifter with his feet wide and hands near the lower back. he pays careful attention to the bar and makes sure the lifter does not fall backwards. this is most likely a spotter for
a. an overhead press
b. a dead lift
c. a squat
d. a bench press

C. a squat

Explanation:

A squat is a lower body exercise which may require a spotter to stand near the squatter to ensure the lifter does not fall backwards.  

A bench press or an overhead press does not require the lifter to be in a standing position, but rather in  a lying position. Dead lift which requires leaning forward cannot cause a lifter to fall backwards.