Answer: a. not compare the original and the new prices without knowing what cost conditions exist in the industry.
Explanation:
If there is a reduction in the demand of comsumer occurs in a purely competitive industry that is initially in long-run equilibrium, we can not compare the original and the new prices without knowing what cost conditions exist in the industry.
It should be noted that the long-run equilibrium for a purely competitive industry occurs where the price intersects both the marginal cost curve and also the lowest point of its average cost curve. At this point, the firm will make zero economic profit.
