Answer:
This is best explained by the incentive theory.
Explanation:
The incentive theory is one of the theories of motivation that help us understand what drives human behavior. Incentive theory, as stated in the question, proposes that behavior is motivated by external goals and our human desire for positive reinforcements.
In this case, Carrie had no motivation to continue in her current job because it didin't give her anymore incentives, but hen she is given a raise, a positive reinforcement, she becomes more interested in her job. Using the incentive theory we can interpret that money acted as an incentive for a behavior.