The Marginal Revenue Curve of a Monopoly Firm Lies Below

The Marginal Revenue curve of a monopoly firm lies below the demand curve because:

A) in order to increase output the firm must lower its price
B) as output increases the firm will need to sell to those who have a lower willingness-to-pay
C) monopolies are often regulated by governments that put limits on market prices
D) the monopoly must lower its price to discourage firms from entering the market