Graph 13-3 the Set of Curves Above Reflect Information About

Graph 13-3
The set of curves above reflect information about the cost structure of a firm. Use this graph to answer the following question(s) .
-Refer to Graph 13-3. Curve A is necessarily U-shaped because of:

A) diminishing marginal product
B) increasing marginal product
C) the fact that decreasing marginal product follows increasing marginal product
D) the fact that increasing marginal product follows decreasing marginal product