Answer:
C). Negative Reinforcement.
Step-by-step explanation:
Negative reinforcement is described as crucial element of 'operant conditioning' as it involves the removal or eviction of a negative result or aversive stimulus in order to promote or reinforce a particular behavior.
In the given situation, it could be stated that the studying behavior has been conditioned through 'negative reinforcement' as the negative outcome(anxiety due to bad grades) is being removed by accomplishing the learning objectives to strengthen or reinforce the favorable response(avoid bad grades) in the exams. Thus, option C is the correct answer.