You push very hard on a heavy desk, trying to move it. you do work on the desk:

a. only if it doesn't move.
b. whether or not it moves, as long as you are exerting a force.
c. only if it starts moving.
d. never—it does work on you.

(C) Only if it starts moving

Explanation:

We know that work done is given by

So there are two case in which work done is zero

First case is that when force and displacement are perpendicular to each other

And other case is that when there is no displacement

So for work to be done there must have displacement, if there is no displacement then there is no work done

So option (c) will be the correct option