For each of the following characteristics, say whether it describes a perfectly competitive firm, a monopolistically competitive firm, both, or neither.
a. Sells a product differentiated from that of its competitors
b. Has marginal revenue less than price
c. Earns economic profit in the long run
d. Produces at the minimum of average total cost in the long run
e. Equates marginal revenue and marginal cost
f. Charges a price above marginal cost