To which one or more of the following situations do the time-dilation and length-contraction equations apply?

(a) With respect to an inertial frame, two observers have different constant accelerations.

(b) With respect to an inertial frame, two observers have the same constant acceleration.

(c) With respect to an inertial frame, two observers are moving with different constant velocities.

(d) With respect to an inertial frame, one observer has a constant velocity, and another observer has a constant acceleration.

(e) All of the above.