In its most energetic phase, a quasar can probably only last:
A)a few days.
B)a few years.
C)a few thousand years.
D)a few million years.
E)a few billion years.

Question

Quizplus · Accepted Answer

Quasars are powered by supermassive black holes that are accreting huge amounts of matter. This process is highly energetic and can release huge amounts of radiation. However, the fuel eventually runs out and the quasar fades away. Based on current understanding of the fuel supply and energy output of quasars, their most energetic phase probably only lasts a few million years. Quasars are powered by supermassive black holes at the centers of galaxies. As matter falls towards the black hole, it heats up and emits large amounts of radiation. This process can continue for millions of years, making D the best choice.

In Its Most Energetic Phase, a Quasar Can Probably Only