Which of the Following Is Not True of Quasars

Which of the following is not true of quasars?

A) The light produced by quasars comes from an accretion disk surrounding a supermassive black hole.
B) Quasars were more common in the past.
C) Some quasars are more than a thousand times more luminous than the Milky Way.
D) Some quasars can change their brightness on the timescale of hours.
E) Quasars are powered by the intense production of large numbers of stars that can only be sustained for a relatively short time.