The Figure Given Below Shows the Aggregate Demand and Supply

Multiple Choice

The figure given below shows the aggregate demand and supply curves of a perfectly competitive market.Figure 10.7

-A clothing store can sell two shirts for $20 each or three shirts for $18 each. At a quantity of three shirts sold, marginal revenue is _____.

A) $18
B) $14
C) $54
D) $20
E) $44