The perfectly competitive firm, whose total revenue $($TR$)$ and total cost $($TC$)$ curves are

shown on the right, should produce

A$.7$ units, since that is where its costs will be minimized.

B$.$ either $7$ or $31$ units, since MC $=$ MR at both levels of production.

C$.31$ units, since that is where $MC=MR$ and $MC$ is increasing.

D$.31$ units, since that is where MC $=$ MR and MC is decreasing.

E$.7$ units, since that is where $MC=p.$