Concept:A perfect market implies perfect competition, where a single firm cannot influence the market price.
Explanation:In a perfect market, the firm is a price taker, so its demand curve is perfectly elastic at the market price
P.
This gives
AR=P and
MR=P.
Thus,
P=AR=MR.
Profit maximisation occurs where marginal revenue equals marginal cost:
MR=MC.
Combining the two conditions gives
P=MR=MC.
Among the options, only option D shows exactly this relation.
Options A, B, and C do not describe the equilibrium condition of a perfectly competitive firm.
Answer:D.
P=MR=MC