Fast Radio Bursts Are Thought to Originate from Outside the Milky

Multiple Choice

Fast radio bursts are thought to originate from outside the Milky Way. Why have astronomers reached this conclusion?

A) No source in the Galaxy could produce such prodigious energy and be invisible at other wavelengths.
B) The bursts experience time dilation.
C) The bursts are observed at a wide range of declinations and right ascensions.
D) The bursts are exceptionally luminous.