"now the trumpet summons us again--not as a call to bear arms, though arms we need--not as a call to battle, though embattled we are-- but a call to bear the burden of a long twilight struggle, year in and year out, "rejoicing in hope, patient in tribulation"--a struggle against the common enemies of man: tyranny, poverty, disease and war itself."

what makes this part of the speech so effective in reinforcing kennedy's message?
a. the use of sarcasm
b. the use of repetition
c. the glittering generalities
d. the rhetorical question