[单选题]
One of Einstein's pos. 3uwb1uico p i,( tg d.7d+:nicwmyx0tulates in bzxo7- v8y;y gformulating the special theory of relativity was that the laws of physics are the sbozv 7gx;-y8yame in reference frames that
A. accelerate.
B. move at constant velocity with respect to an inertial frame.
C. oscillate.
D. are stationary, but not in moving frames.