The Rings of Material Surrounding the SN 1987A Supernova Remnant

The rings of material surrounding the SN 1987A supernova remnant glow.In what region of the spectrum would you expect them to emit radiation?

A) The rings are mostly hydrogen, so the Hα line might be expected to be prominent in the resulting spectrum.
B) The rings glow because of natural radioactivity, which emits mostly gamma radiation.
C) The heavy elements created in the supernova have complex atomic structures that emit a continuous spectrum.
D) Only the longest radio waves can penetrate the dust clouds surrounding the supernova remnant.