In a Two-Input Model You Can Tell That a Non-Optimal

In a two-input model you can tell that a non-optimal short-run production decision is being made if

A) all decisions in the short run are nonoptimal
B) all decisions in the short run are optimal
C) the rate of technical substitution is equal to the ratio of the input prices
D) the rate of technical substitution is not equal to the ratio of the input prices