Which of the Following Statements Is Correct About the Demand

Which of the following statements is correct about the demand curve of the perfectly competitive industry?

A) The demand curve of the perfectly competitive industry is horizontal as are the demand curves facing the individual firms.
B) The market demand curve of perfect competition is vertical because the individual consumers are buying a homogeneous product.
C) The market demand curve of the perfectly competitive industry is downward sloping while the demand curve facing an individual firm is horizontal.
D) The market demand curve of the perfectly competitive industry is downward sloping, so the demand curves of the individual firms are also downward sloping.