Which of the following is false?

a. A perfectly competitive firm cannot sell at any price higher than the current market price and would not knowingly charge a lower price because it could sell all it wants at the market price.

b. In a perfectly competitive market, individual sellers can change their output without altering the market price.

c. In a perfectly competitive industry, the firm’s demand curve is downward sloping.

d. The perfectly competitive model does not assume any knowledge on the part of individual buyers and sellers about market demand and supply—they only have to know the price of the good they sell.