What Is a Quasar

What is a quasar?

A) a star- like object that actually represents a bright patch of gas in the Milky Way
B) the name given to the largest objects in the Kuiper Belt
C) a very large galaxy thought to be formed by the merger of several smaller galaxies, resulting in a quick burst of star formation
D) another name for very bright stars of spectral type O
E) the extremely bright center of a distant galaxy, thought to be powered by a supermassive black hole