If capital is a variable input in production, the law of diminishing marginal returns implies that in the short run

A) capitalʹs marginal product is constant.
B) capitalʹs marginal product decreases after a certain point.
C) total product is negative.
D) total product is negative after a certain point has been reached.

The law of diminishing marginal returns states that as more units of a variable input (in this case, capital) are added to fixed amounts of other inputs, the additional output produced by each new unit of the variable input will eventually decrease. This implies that capital's marginal product decreases after a certain point, not that it remains constant or that total product becomes negative.