Which of the Following Statements Is True

Which of the following statements is true?

A) The average product of labor is at its maximum when the average product of labor equals the marginal product of labor.
B) The average product of labor is at its minimum when the average product of labor equals the marginal product of labor.
C) The average product of labor tells us how much output changes as the quantity of workers hired changes.
D) Whenever the marginal product of labor is greater than the average product of labor the average product of labor must be decreasing.