Iago excels at preying on people's weaknesses, but is there evidence that Othello is susceptible to jealousy? Why do you think Iago selected jealousy as his exploitable weakness?

Cassio laments that he has lost his reputation, which is very dear to him. Iago tries to convince him that a reputation means little; and, if he talks to Desdemona, maybe he can get her to vouch for him with Othello. This will help Iago hint that Desdemona and Cassio are together, which will enrage Othello. Iago knows that Othello is a man of absolutes. Othello worships Desdemona or he hates her: there is no in-between. The smallest seed of discontent will germinate and grow in Othello's mind. Iago knows exactly what he is doing by aligning Desdemona and Cassio together. Othello will come to the only conclusion that is possible for him.