Answer:
3 but see below.
Step-by-step explanation:
This is a really hard question. Kennedy always restated what he wanted to say in a different way. He was a great speaker -- one of America's most literate men.
I would pick 3. It is a heartfelt statement that includes the entire nation. And it states (in his mind) the most important reason for undertaking a moon mission.
But look at the other answers.
Isn't 4 a prophetic dream? Don't you think it turned out to be true?
And 2 also takes in the entire nation. I just think 3 is more clearly stated.
The poetry in one is a very strong argument. It is typical Kennedy at his best.
I still pick 3 but don't be surprised if your instructor does not agree.