Which of the following inventions, if it could be perfected and manufactured at a viable cost, would address the most challenges to human interstellar space travel, as presented in the passage?

A. ram-scoop drive that can accelerate a spacecraft of any size to four-fifths of the speed of light within 24 hours

B. cold-sleep capsule that essentially halts the passage of time for human inhabitants while protecting them from all physical harm

C. sustainable biosphere that reliably generates healthy food and automatically cleans air and water

D. neutrino-based communications system that permits instantaneous communication across any distance without any relativistic time dilation

E. n impervious force field that protects the ship and its inhabitants from radiation, meteor strikes, or hostile alien attacks