While Playing a Game, a 9-Month-Old Infant Tries to Grab

While playing a game, a 9-month-old infant tries to grab slow-moving balls, but doesn't try for fast-moving balls. Research by van Hof suggests that 9-month-olds _____.

A) can catch, and so have experience with which balls are catchable
B) understand inertia intuitively, and realize that it is easier to stop a slower ball
C) cannot see the faster moving balls clearly, so they don't try for them
D) understand that slower moving balls afford catching more than faster moving balls do