Which of the products below is towards the spectrum of perfectly competitive industry?

In the short run, firms expand their production when the price level rises because

A) the money wage rate remains constant so the higher prices for their products makes it profitable for firms to expand production. B) each firm must keep its production up to the level of its rivals, and some firms will expand production as the price level increases. C) the higher prices allow the firm to hire more workers by offering higher wages, thereby increasing productivity and profits. D) firms can increase their profits by increasing their maintenance.

When a perfectly competitive industry is in long-run equilibrium, firms maximize profits, and entry forces the price down

a. until all loss making firms leave the industry. b. until each firm can earn acceptable level of economic profit. c. until price becomes tangent to the long run average cost curve. d. until the long average cost curve rises above the demand curve.