It was a voluntary gesture.

Answer: Option A

Voluntary : done, given, or acting of one's own free will.
Compulsory : required by law or a rule; obligatory.
Violent : using or involving physical force intended to hurt, damage, or kill someone or something.
Deliberate : done consciously and intentionally.
Valuable : worth a great deal of money.

Antonym of Voluntary is Compulsory