Suppose That in the Short Run, the Firm Which Has

Suppose that in the short run, the firm which has production function F(L, M) = 4L^1/2M^1/2 must use 9 machines.If the cost of labor is $5 per unit and the cost of machines is $6 per unit, the short-run total cost of producing 84 units of output is

A) $598.
B) $420.
C) $462.
D) $504.
E) $299.