Answer: A. persuade the troops that this cause is so worthy that she is willing to sacrifice her own life.
In this excerpt, Queen Elizabeth is trying to persuade the troops that the cause she refers to is so worthy she is willing to sacrifice her own life. She states that she is willing to "to live or die among you all, to lay down for my God, and for my kingdoms, and for my people, my honour, and my blood." She wants to encourage the troops to fight by telling them how important their duty is and how much she values the sacrifice of the soldiers.