A Truck Has a Crate in Its Cargo Bed

Multiple Choice

A truck has a crate in its cargo bed. If the truck accelerates forward and the crate does NOT move, in which of these directions is the frictional force that the floor of the cargo bed exerts on the crate?

A) downward
B) forward
C) backward
D) There is no friction force because the crate is not moving with respect to the floor of the cargo bed.