What Evidence Suggests That Long Gamma Ray Bursts Originate from Supernovae

What evidence suggests that long gamma ray bursts originate from supernovae of stars massive enough to form black holes?

A) Rapid observations in other wavelengths show that some gamma ray bursts coincide with points showing typical supernova light curves.
B) Some gamma ray bursts have been found to originate with galaxies that are actively forming stars, and would thus have a few very massive (but short lived) stars.
C) The locations of gamma ray bursts suddenly begin blocking light from more distant stars.
D) A and B
E) B and C