The Short,narrow Circular Arcs of Light That Seem to Surround

Multiple Choice

The short,narrow circular arcs of light that seem to surround some galaxies are caused by

A) supernova explosions within the galaxies,the arcs representing parts of the shells of gas exploded outward by the supernova.
B) gravitational lensing by the galaxies of the light from a single,distant object very far behind the galaxy.
C) the shaping of regions of dense matter as it is attracted and condensed into the central black hole of the galaxies.
D) blue gas clouds surrounding the galaxies.