Perfectly Competitive Firms Are Price Takers Because

Perfectly competitive firms are price takers because

A) all small firms must take the price set by the largest firm in the market
B) firms take the price that government determines is a "fair" price
C) each firm is small and goods are perfect substitutes for one another
D) free entry and exit in the short run creates a constant market price in the long run
E) high barriers to entry force firms to compete by charging lower prices than other firms in the industry