Which of the Following Is False of Perfectly Competitive Firms

Which of the following is false of perfectly competitive firms?

A) A perfectly competitive market is approximated most closely in highly organized markets for securities and agricultural commodities.
B) The perfectly competitive model does not require any knowledge on the part of individual buyers and sellers about market demand and supply curves.
C) Because perfectly competitive firms are price takers, each firm's demand curve remains unchanged even when the market price changes.
D) In a perfectly competitive market, marginal revenue is constant and equal to the market price.