Answer: A.
Students face disappointment if they lose while competing.
Step-by-step explanation:
I think it's A, because in the passage it says..
"Moreover, it is obvious that any competition will have only one winner, and the others have to brace themselves for disappointment. Sometimes, even though a person may perform well, he or she may lose a competition to someone who performs slightly better. This disappointment can affect the confidence of the competitor, and therefore, his or her performance."