Karen graduated from college four years ago and has been working at Betaphy Inc. ever since. She has consistently received good performance evaluations for the quality of her work. She recently found out that her company hired a fresh college graduate with no experience at a salary higher than hers. Which of the following theories will Karen most likely use to evaluate this situation?
a) reinforcement
b) goal setting
c) expectancy
d) equity
e) operant conditioning