When reading the play "Othello" and looking at the idea of decisions, I think it might be better to examine why decisions were made by certain characters, the actions taken as a result of those decisions, and the repercussions of those choices. Planning such an essay, you could look at Iago and why he felt the need to take down Othello (Iago's superiority complex, his belief that Othello treated him badly, his desire for power), his plan to do this, and what happened as a result. Same thing goes for Othello's choice to kill Desdemona, including everything leading up to that choice. You could also look at Emelia's final choice to turn Iago in—what pushed her in the end to finally assert herself and stand up to him. The thesis could be the exploration of the characters and why they did what they did.