When Caroline's Dress Factory Hires Two Workers, the Total Product

Multiple Choice

When Caroline's dress factory hires two workers, the total product is 50 dresses. When she hires three workers, total product is 60, and when she hires four workers, total product is 75. The slope of the marginal product curve when two to four workers are hired is:

A) upward.
B) downward.
C) vertical.
D) horizontal.