The correct answer is A. First of all
Step-by-step explanation:
In speeches, introductions outline the main points that will be cover and let the audience know the focus of the speech. Additionally, introductions may include context clues to help the audience understand this is the beginning of the speech such as to begin with, firstly, or first of all. In the case, of the Inaugural Address the prhase "first of all" in "So, first of all, let me assert my firm belief that the only thing we have to fear is fear itself" acts as context clues to show the audience this is the introduction of the speech and highly the first point of it.