If 1 orchard, 7 workers, and 3 tons of fertilizer yield 1000 bushels of peaches, while 1 orchard, 7 workers and 4 tons of fertilizer yield 1300 bushels,

a) the average product of labour equals 1150 bushels.

b) the marginal product of labour cannot be calculated.

c) the average product of fertilizer equals 1150 bushels.

d) the marginal product of fertilizer cannot be calculated.