A non-discriminating monopolist is selling 6 units at a price of$12. If the marginal revenue of the seventh unit is $5, then:

price of the seventh unit is $10.

price of the seventh unit is $11.

price of the seventh unit is greater than $12.

price of the seventh unit is $5.

Assuming the demand curve that a pure monopolist faces isdownward-sloping, its total revenue:

is rising.

is falling.

may be either rising or falling.

must be negative.