As New Firms Enter a Monopolistically Competitive Industry, the Demand

As new firms enter a monopolistically competitive industry, the demand

A) and marginal revenue curves facing each firm begin to shift to the right.
B) curve facing each firm begins to shift to the right but the marginal revenue curve remains constant.
C) and marginal revenue curves facing each firm begin to shift to the left.
D) curve facing each firm shifts to the left, but the marginal revenue curve remains constant.