At the optimum combination of two inputs, Select one:

a. the slopes of the isoquant and isocost curves are equal.

b. All of these

c. costs are minimized for the production of a given output.

d. the slopes of the isoquant and isocost curves are equal and the marginal rate of technical substitution equals the ratio of input prices only e. the marginal rate of technical substitution equals the ratio of input prices.