You are an efficiency expert hired by a manufacturing firm that uses $K$ and $L$ as inputs. The firm produces and sells a given output. If $w=$$$40,r=$$$100,M{P}_L=20,$ and $M{P}_K=40$ the firm:

A$.$ is cost minimizing.

B$.$ should use less $L$ and more $K$ to cost minimize.

C$.$ should use more $L$ and less $K$ to cost minimize.

D$.$ is profit maximizing but not cost minimizing.