What Shape of Demand Curves Do Competitive Firms Have,and How

Multiple Choice

What shape of demand curves do competitive firms have,and how much output can they sell

A) They have downward-sloping demand curves, and they can sell as much output as they desire at the market price.
B) They have downward-sloping demand curves, and they can sell only a limited quantity of output at each price.
C) They have horizontal demand curves, and they can sell as much output as they desire at the market price.
D) They have horizontal demand curves, and they can sell only a limited quantity of output at each price.