The market price of a labour is $15 per hour, and the rental cost of capital is S60 per hour. A firm's production function is Q= 15L^0.5K^-0.5.

If the fim uses 120 labourers per hour, then it will pair the labour with _________ units of capital to maximize profit.

Select one

a. 48 300

b. 300

c. 18.75

d.768