In its purest form, consumers in a perfectly competitive market will act as if they only care about the price of a good when deciding who to buy from. This is because?

A each firm will try to cut its prices to increase its market share.

B each firm can expect to earn some economic profit.

C the demand for each firm's product is perfectly inelastic.

D each firm's output is a perfect substitute of any other firm's.

E consumers do not care about quality differences in goods.