In a Natural Monopoly, Marginal Cost Will

In a natural monopoly, marginal cost will

A) respond to average cost.
B) fall below average cost when the firm produces the last unit of output.
C) rise above average cost when the firm produces the last unit of output.
D) equal average cost when the firm produces the last unit of output.
E) sometimes fall below and sometimes rise above average cost when the firm produces the last unit of output.