Please help a. s.a. p. (answer has to be 100% correct btw)

2. Which of the sentences contain both an independent and a dependent clause?
A. He was listening intently to the radio, and he didn't hear the doorbell.
B. As she entered the auditorium, she tripped over a backpack that had been carelessly left in the doorway.
C. Visiting the aquarium turned out to be quite an adventure; I enjoyed it thoroughly.
D. We understand the environmental concerns of the farming community, but we are aware that business owners have another point of view.

Option B is the correct answer

Explanation:

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."