In the Middle of a Difficult Exam,Robert Tells His Teacher

In the middle of a difficult exam,Robert tells his teacher that his stomach hurts,and the teacher immediately sends him to the school nurse. On several later occasions when he has a difficult test or assignment,Robert again tells his teacher that he doesn't feel well. Each time he is sent to the school nurse before he has completed his work. From an operant conditioning perspective,we can say that Robert is:

A) Experiencing removal punishment for complaining about his stomach.
B) Being negatively reinforced for complaining about his stomach.
C) Being intermittently reinforced for complaining about his stomach.
D) Showing a tendency to delay gratification.