Multi choice Economics question?

Monopolistically competitive is kind of an odd term, but I think it means that the seller faces a downward-sloping demand curve - the good he sells has imperfect substitutes, rather than the perfect substitutes faced by a seller in competitive markets. If demand is downward-sloping, price is always less than marginal revenue unless the seller can practice perfect price discrimination. Since MR=MC is a profit-maximizing rule and P>MR, we know that P>MC at the margin. That is, a seller would be better of selling another unit IF he didn't have to lower the price to prior buyers in order to sell that unit.