His craven behaviour makes him an object of mockery

Answer: Option B

Silly : having or showing a lack of common sense or judgement; absurd and foolish.
Cowardly : lacking courage.
Indecent : not conforming with generally accepted standards of behaviour, especially in relation to sexual matters.
Mean : intend to convey or refer to (a particular thing); signify.
Craven : contemptibly lacking in courage; cowardly.

Synonym of Craven is Cowardly