T meson at rest decays into two photons, which moves along the x -axis. they are both detected simultaneously after a time, t = 10s. in an inertial frame moving

T meson at rest decays into two photons, which moves along the x -axis. They are both detected simultaneously after a time, t = 10s. In an inertial frame moving with a velocity v=0.6c in the direction of one of the photons, the time interval between the two detections is a) 15c a) (b) Os (c) 10s (d) 20s