He thought gambling was a vice.

A. courtesy

B. kindness

C. virtue

D. goodness

Answer: Option C

Solution(By Examveda Team)

Vice : immoral or wicked behaviour.
Courtesy : the showing of politeness in one's attitude and behaviour towards others.
Kindness : the quality of being friendly, generous, and considerate.
Virtue : behaviour showing high moral standards.
Goodness : the quality of being morally good or virtuous.

Antonym of Vice is Virtue