Read the following sentence and choose the best alternative which should replace the italicized part of the sentence.
The tremendous insight of Einstein was that the passage of time does not appear to be the same while standing still as it does to a person traveling at a speed which is a significant fraction of the speed of light.

A

while standing still as it does to a person traveling

B

to a person standing still as to a person traveling

C

to a person who is standing still as a person who is traveling

D

while standing still as to traveling

E

to a person standing still as to a person who travels