Which is used by the girl to produce motion in the bookshelf as shown in the picture below
A.Force
B.Friction
C.A pulley
D.Gravity
![Which Is Used By The Girl To Produce Motion In The Bookshelf As Shown In The Picture BelowAForceBFrictionCA PulleyDGravity class=](https://ph-static.z-dn.net/files/d8f/1258c6f34fe93f0216c8f842bf256609.jpg)