Evidence for the Conclusion That the Longer-Living Gamma-Ray Bursts Are

Evidence for the conclusion that the longer-living gamma-ray bursts are very distant comes from the

A) extreme redshift of emission lines in the visible spectrum detected after a gamma-ray burst.
B) delay in the arrival of the visible pulse behind the gamma-ray pulse, caused by the passage of the light through optically thick intergalactic material.
C) spread in arrival times of different gamma-ray photon energies, indicating a long passage through intergalactic gas.
D) observations of afterglows inside distant galaxies.