Among these unlucky deeds. the immediate one is _________

The term "immediate" in the question suggests that we are looking for an act that directly led to a negative outcome or consequence. Among the unlucky deeds listed, the immediate one is the killing of Desdemona. This is because the murder of Desdemona is the direct cause of the tragic ending of the play, as it leads to the discovery of Iago's lies and the suicide of Othello. The other deeds listed may have contributed to the overall tragic outcome, but they were not the immediate cause of the tragedy. Therefore, the correct answer is: "the killing of Desdemona".