Which is true about comparing clocks in two different inertial systems?
A. Clocks in one system appear to run backwards when viewed from the other.
B. The clocks are all synchronized.
C. There is no way to know the relation between clocks in the two systems.
D. Clocks in one system appear to run faster when viewed from the other.
E. Clocks in one system appear to run slower when viewed from the other.