Answer:
D.
Step-by-step explanation:
Cold sweat is a state of sweating induced by fear or anxiety, so D would be the correct answer.
A is wrong because there is no humor in panicking and sweating during the exam for which the person had not studied.
B is wrong because the cause of the character's panic is not cold sweat but his realization that he will fail the exam.
C is wrong because there is no excitement in the realization that failure is inevitable.