The correct answer is B. They feel uncertain about the future.
Step-by-step explanation:
The audience of a speech refers to the group of people a speaker is directly addressing the features this group of people has. In the text presented, one national leader states the country is at war and their enemy has been winning this war "Recently the enemy has been prevailing, as evidenced by their victories last week", despite this, he believes the war can be won the U.S. " But I can assure you with the faith only an American can have that we will prevail". This shows the speaker knows the audience is aware of the war and the victories of the enemy and this main purpose is to reassure the audience the result will change as they probably feel uncertain about the future. Therefore, it is probably the speaker assumes about the audience that this feels uncertain about the future and because of this the speaker wants to give hope to the audience and tell them everything will improve.