Spring Airlines is a small budget airline that is based in China. The company has a strict rule against passengers bringing any food or beverage on board with them. In a country where meal time is extremely important, this has caused some passengers to slap, throttle, and insult stewardesses who tried to enforce this rule. The tenacity with which the company's employees enforce this ruling is based on how the employees predict customers will react to the news. This is an application of the _________ theory.

A. Psychological
B. Estimation
C. Equity
D. Expectancy
E. Reevaluation