Answer :
Answer: Why do single firms in perfectly competitive markets face horizontal demand curves? A) With many firms selling an identical product single firms have no effect on market price.
Explanation: A perfectly competitive market has different buyers and sellers who all sell the same product and there is nothing stopping new firms from entering and selling the same product. A horizontal demand curve happens when a product is said to be perfectly elastic meaning that the price of a good or service can not rise above the market price or the demand will be at zero.