Answer:
The rhetorical technique used in this excerpt is a. shift.
Explanation:
Shift as a rhetorical technique refers to a change in the mood, style, or tone of what is being said. It is usually started with a conjunction that expresses such alteration and contrast, such as "yet", "but", "although", etc. In this particular speech, the initial mood is one of sadness and exhaustion. Churchill focuses on the disasters, the dangers, and the losses the war brought. From the moment he says "yet" on, however, the mood shifts to a positive, assertive one, in which he tells us about the high morale of the Allies. Against all odds, in contrast with everything that had been said, we are now told the Allies kept their spirits up.