For Gravitational Lensing of a Distant Quasar to Occur, the Galaxy

Multiple Choice

For gravitational lensing of a distant quasar to occur, the galaxy producing the lensing must

A) be rotating rapidly to produce the requisite curvature of space to bend the light beam.
B) be almost perfectly placed on a line between Earth and the quasar.
C) contain a supermassive black hole at its center.
D) be a dwarf galaxy; otherwise the quasar's light cannot pass through it and reach Earth.