The Marginal Product of Labor Is the Increase in Total

The marginal product of labor is the increase in total product from a

A) one unit increase in the quantity of labor, while holding the quantity of other inputs constant.
B) one unit increase in the quantity of labor, while also increasing the quantity of other inputs by one unit.
C) one dollar increase in the wage rate, while holding the price of other inputs constant.
D) one percent increase in the wage rate, while also increasing the price of other inputs by one percent.