A benevolent social planner (ie, someone who chooses an allocation instead of the market) would choose the allocation that

A. picks the unique input combination that equates the MRTS of the two goods.

B. maximizes firm profits subject to the PPF, even if prices are out of equilibrium.

C. maximizes the representative consumer's utility subject to being on the PPF.

D. maximizes the representative consumer's utility subject to their budget constraint, even if prices are out of equilibrium.