The Figure Given Below Shows the Revenue and Cost Curves

Multiple Choice

The figure given below shows the revenue and cost curves of a perfectly competitive firm.Figure 10.5
MC: Marginal cost curve
MR: Marginal revenue curve.ATC: Average-total-cost curve
AVC: Average-variable-cost curve
-Why do the perfectly competitive firms earn only normal profits in the long run?

A) Entry or exit is barred
B) Firms produce identical products
C) A large number of buyers and sellers exist in the market
D) Aggregate demand remains constant
E) There is free entry and exit of firms