Four People Are Sitting at the Lettered Positions on the Rim

Multiple Choice

Four people are sitting at the lettered positions on the rim of a merry-go-round shown below that is slowly turning clockwise. You throw a fairly massive ball horizontally to one of these people, who catches it. To which person should you throw the ball so that catching it most effectively increases the merry-go-round's rotation rate?

A) A
B) B
C) C
D) D