The correct option is C meanness
Magnanimity means the fact or condition of being magnanimous; generosity. The opposite of magnanimity is meanness, or unkindness, spitefulness, or unfairness. Hence, Option C is correct. Among the rest of the options, poverty means the state of being extremely poor, jealousy means resentment against a rival, a person enjoying success or advantage, enmity means a state or feeling of active opposition or hostility. These options do not express this antonym, hence incorrect.