That was a dauntless action!

Answer: Option B

Dauntless : showing fearlessness and determination.
Devious : showing a skilful use of underhand tactics to achieve goals.
Irresolute : showing or feeling hesitancy; uncertain.
Secretive : (of a person or an organization) inclined to conceal feelings and intentions or not to disclose information.
Cowardly : lacking courage.

Antonym of Dauntless is Irresolute