I'm not the best with these, but I'd say It's D. (I'd wait till others answer this. I'm not very good with these.)
Answer: A
Explanation:
A is not relevant because the size of the international space station has nothing to do with the physiological effects of traveling IN space.
If this is a !multiple choice questions I would say B. Observe all the characters of the story from the outside. I hope this helps and I got it right. Good luck!