If a Single-Price Monopolist Has to Lower Price to Sell

If a single-price monopolist has to lower price to sell an additional unit of its good, and it charges the same price for all units of its good, it follows that

A) its demand curve will be its marginal revenue curve.
B) it will maximize profits by maximizing revenue.
C) it will sell its good for a price above average total cost.
D) its demand curve will lie above its marginal revenue curve.