My parents were confident of my success in the examination.

The correct answer is A. worried.

Worried is the feeling of anxiety or concern about something that might happen. In this case, the parents are worried about their child’s success in the examination.

B. pessimistic is the tendency to see the worst in things. In this case, the parents would not be optimistic about their child’s chances of success.

C. diffident is the lack of confidence or assurance. In this case, the parents would not be confident in their child’s ability to succeed.

D. depressed is the feeling of sadness and hopelessness. In this case, the parents would be very unhappy about their child’s chances of success.