Assume a production function with only two inputs, capital and labor. In this case, the concept of a diminishing marginal product of capital implies that

A$)$ as less capital is being used, more and more labor has to be employed to increase output

B$)$ as both labor and capital inputs are increased, output increases but at a decreasing rate

C$)$ as the amount of capital is increased and the amount of labor remains fixed, output increases but at a decreasing rate

D$)$ as the amount of capital increases and the amount of labor remains fixed, output cannot increase

E$)$ labor inputs have a bigger impact on increasing output than capital inputs.