Out of the four alternatives, select the alternative which is the best substitute of the phrase.
"Involving immoral or dishonourable actions and motives"

* Sordid means involving ignoble, immoral, or dishonorable actions and motives.
Redoubt means a temporary or supplementary fortification structure.

Scrupulous means diligent, thorough, and extremely attentive to details or moral integrity.

Immaculate means perfectly clean, neat, or pure.