In this question each one proposed his own assertion. But Edward didn't stress reliability outweighed economic consideration.
I think banerjeea's opinion is right.
Edward proposed the reliability consideration and assumed that there is no serious impediment (economic consideration) to transport people into space, but the economic issue was raised by Teresa.
Yes, I agree it can be argued this way. In fact E's point is definitely wrong because while T is comparing manned spaceship with other means of space flight, E compares reliability of human transportation
. If the topic of discussion is whether manned spaceflight has potential as a means of space flight then E's definitely totally out of the point, not so much in that he made certain assumptions, but in that he has totally missed the point. Compare the different choices given though, I suppose D is the closest.
Keep on asking, and it will be given you;
keep on seeking, and you will find;
keep on knocking, and it will be opened to you.