If a Monopolist Increases Quantity by One Unit, but Sells

If a monopolist increases quantity by one unit, but sells the increased output at a slightly lower price,

A) marginal revenue is affected by adding one additional unit sold at the new price.
B) all the previous units, which used to sell at a higher price, now sell for more.
C) the marginal revenue of selling a unit is more than the price of the unit.
D) because of higher output the marginal revenue curve is above the demand curve.