[单选题]
One of Einstein's postulates in formulating the specia0 *yq3jwvezp qfj0 tn qa;*o/;l theory of rela-usb.t d.6ngptivity was that the laws of physics are th.sg pd-b.u 6nte same 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.