It Is Usually Assumed That a Perfectly Competitive Firm's Supply

It is usually assumed that a perfectly competitive firm's supply curve is given by its marginal cost curve.In order for this to be true,which of the following additional assumptions are necessary?
I.That the firm seek to maximize profits.
II.That the marginal cost curve be positively sloped.
III.That price exceeds average variable cost.
IV.That price exceeds average total cost.

A) I and II only.
B) I and II but not III and IV.
C) I and III but not II and IV.
D) I, II and III, but not IV.