OE
The word “Despite” at the beginning of the sentence indicates that the blank must oppose the encouragement of a con artist (someone who tricks people out of money)—that is, the “mark” is doubtful about the con artist’s claims. (A mark is someone who is a target of a criminal or con artist.) “Skeptical” and “leery” match this meaning. “Optimistic” and “enthused” create a pair, but do not fit the required meaning of the sentence. And the remaining words neither fit the intended meaning of the sentence nor form a pair: “irascible” means easily angered, while “jaundiced” most commonly means yellow in complexion (from the medical condition) but can also mean bitter or envious.
Answer: D,F