In a perfectly competitive market, the process of entry and exit will end when

(i)

accounting profits are zero.

(ii)

economic profits are zero.

(iii)

price equals minimum marginal cost.

(iv)

price equals minimum average total cost

a) (i) and (ii) only

b) (ii) and (iii) only

c) all are correct

d) (ii) and (iv) only