Colons are used to
a. indicate omissions
b. add words
c. set apart citations
d. introduce longer quotations

the president was the speaker and it was a great part of history.

explanation:

video of the national aeronautic space administration's (nasa) coverage of president john f. kennedy’s address at rice university, houston, texas, concerning the nation's efforts in space exploration. in his speech the president discusses the necessity for the united states to become an international leader in space exploration and famously states, "we choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard."

c is the answer because first she would blush to make the reader wonder why which they find out in the next line.