Mark sees Anna moving eastward at 2.50 x 10^8 m/s. At the same time, Anna sees Rachel moving eastward at 2.50 x 10^8 m/x.
What is Rachel's speed as measured by Mark?
A) 0.00 x 10^8 m/s
B) 2.50 x 10^8 m/s
C) 2.95 x 10^8 m/s
D) 5.00 x 10^8 m/s