Answer:
d. Both a and b are correct.
Step-by-step explanation:
- When a firm is entering a market with perfect competition the total revenue of the must be equal to the total costs of the firm production and thus the profits must be equal to zero.
- As a perfect competition is characterized by a large number of buyers, homogenous products, rational buyers, no externalities, no barriers to entry or exit. Thus the seller makes a normal profit on the level of return and investment and represents an opportunity cost.