Many Bright Radio Sources at Very Large Distances from the Sun

Multiple Choice

Many bright radio sources at very large distances from the Sun appear to emit energy from two relatively widely spaced sources. What mechanism is thought to produce these double-radio emission regions?

A) Two oppositely directed beams of light and radio energy illuminate the intergalactic dust and gas.
B) Two oppositely directed plasma jets from a central source produce radio energy as the plasma slows down.
C) These sources are two galaxies orbiting each other like binary stars.
D) The sources are in fact a single source and its reflection in a dense intergalactic gas and dust "mirror," or plasma sheet.