Which of the Following Describes a Major Challenge of Interstellar

Multiple Choice

Which of the following describes a major challenge of interstellar travel at near light speed?

A) Asteroid fields floating in interstellar space will present a severe navigational challenge.
B) Supernova explosions could destroy spaceships passing nearby.
C) Time dilation will slow the heartbeats of the crew to a dangerously low rate.
D) Any interstellar journey will take much longer than the lives of the crew members.
E) Atoms and ions in interstellar space will hit the spacecraft like a flood of dangerous cosmic rays.