Answer:
c. faces a downward-sloping demand curve for its product
Step-by-step explanation:
Perfect Competition is a market form, having large no. of sellers, selling homogeneous products at constant prices. So, constant prices imply that their demand curve is horizontal, perfectly elastic.
Monopolistic Competition is a market form, having many sellers, selling slightly differentiated products which are incomplete substitutes of each other. The prices also vary from firm to firm, depending on product quality. So, these firms have usual downward sloping curve, denoting price-demand inverse relationship.