Three crates are being pulled by a force of 3595N across a frictionless roller-conveyor system. The group of crates accelerates to the right at a rate of 1.546(m)/(s^(2)). What is the reason for this acceleration?
A) Friction between the crates and the conveyor
B) The force applied to the crates
C) The weight of the crates
D) The shape of the crates