He did not continue for long with his murky intentions.

Answer: Option C

Dishonest : behaving or prone to behave in an untrustworthy, deceitful, or insincere way.
Dull : lacking interest or excitement.
Lazy : unwilling to work or use energy.
Ominous : giving the worrying impression that something bad is going to happen; threateningly inauspicious.
Murky : obscure or morally questionable.

Synonym of Murky is Dishonest