What Property of the Longer-Living Gamma-Ray Bursts Indicates That They

Multiple Choice

What property of the longer-living gamma-ray bursts indicates that they are located at large ("cosmological") distances from Earth?

A) highly redshifted emission lines seen in their visible spectrum from the burst's nucleus
B) small apparent sizes of the objects producing the bursts
C) absorption lines in the visible spectra of their remnant glow, due to intergalactic clouds between them and Earth
D) faintness of these bursts