Very Early in His Thinking About Relativity, Einstein Asked Himself

Very early in his thinking about relativity, Einstein asked himself what a person would observe if he or she kept up with a lightbeam. In answer to this question, the theory of relativity states that

A) the observer would suddenly undergo a sex change.
B) this is not a valid question because a person cannot move as fast as a lightbeam.
C) time would speed up without limit, and would pass at an "infinite" rate.
D) the light beam would stand still and so time would stand still.
E) the observer own would continue to observe the same laws of physics.