Answer: D. Whether it will become a force for good or ill depends on man, and only if the United States occupies a position of pre-eminence can we help decide whether this new ocean will be a sea of peace or a new terrifying theater of war. (paragraph 6)
Step-by-step explanation:
The sentence above supports the idea that the United States should explore space as this would benefit humanity.
It does this by insinuating that if the United States are not the ones to lead humanity into space, a situation may arise where such exploration would be a force of ill and a terrifying theatre of war. If the U.S. were to lead it however, it would be a force of good and a sea of peace.