The following data show the total output for a firm when different amounts of labour are combined with a fixed amount of capital. Assume the wage per unit of labour is $10 and the cost of the capital is $50. Labour per period 0 1 Total output per period 0 10 30 90 132 150 2 3 4 5 TABLE 7-3 Refer to Table 7-3. The average product of labour when the firm hires 3 units of labour is The average product of labour when the firm hires 4 units of labour is Select one: A. 90; 222 B. 60; 42 C. 90; 132* D. 30; 90 E. 30; 33