Choose the word which is different from the rest.

The answer is E. Morbid.

The other words all refer to actions that are intended to deceive or cheat someone. Treachery is the act of betraying someone’s trust, fraud is the act of deceiving someone in order to gain money or property, deceit is the act of lying or misleading someone, and swindle is the act of tricking someone out of money or property. Morbid is an adjective that means relating to or suggestive of death or disease.

Morbid is the only word in the list that does not refer to an action that is intended to deceive or cheat someone. It is an adjective that describes something that is related to or suggestive of death or disease.