Her modesty prevented her from making her feelings known to him.

Answer: Option A

Modesty : the quality or state of being unassuming in the estimation of one's abilities.
Vanity : excessive pride in or admiration of one's own appearance or achievements.
Superiority : the state of being superior.
Hypocrisy : the practice of claiming to have higher standards or more noble beliefs than is the case.
Arrogance : the quality of being arrogant.

Antonym of Modesty is Vanity