Typically,as a Firm Hires Additional Workers,what Happens to the Marginal

Typically,as a firm hires additional workers,what happens to the marginal product of labour and the value of the marginal product of labour

A) The marginal product of labour and the value of the marginal product of labour both decrease.
B) The marginal product of labour stays constant, and the value of the marginal product of labour decreases.
C) The marginal product of labour decreases, and the value of the marginal product of labour stays constant.
D) The marginal product of labour decreases, and the value of the marginal product of labour increases.