Concept:The phrase refers to committing an act of extreme despair, usually meaning suicide.Explanation:In Shakespeare’s Othello, Gratiano says that Brabantio, Desdemona’s father, would have been shattered by grief if he had lived to witness her death.That overwhelming grief would have led him to a desperate action.Here, “desperate” suggests hopelessness, while “turn” means an act or deed.So “do a desperate turn” means to take one’s own life.Answer:A. commit suicide