Answer:
c. incentive.
Step-by-step explanation:
Based on the information provided within the question it can be said that this sudden change shows the effects of incentives within the experiment. This term refers to a constant motivator for the test subjects which is a reward that the test subjects get if they perform a desired action or outcome. Which in this case the food reward was the incentive that the rats wanted in order to complete the complex maze with less errors.