For a Perfectly Competitive Firm, the Price of Its Good

For a perfectly competitive firm, the price of its good is equal to the firm's marginal revenue because

A) there are only a small number of firms in the market.
B) individual perfectly competitive firms cannot influence the market price by changing their output.
C) the firm's total revenue cannot be changed by anything the firms do.
D) information about price changes is hard to come by for small sellers.
E) price and marginal revenue are the same economic concepts.