Read this excerpt from A Black Hole Is NOT a Hole by Carolyn Cinami DeCristofano.

Reber had just one little problem. To explore the radio energy, he needed a radio telescope—a telescope that could detect invisible radio energy—but there was no such thing at the time. So he invented one. He built it in his backyard in Wheaton, Illinois. Late into the night, Reber probed the sky with his new telescope, using it to locate the source of the mysterious radio energy.

Reber mapped these signals from the sky and shared his findings. Astronomers followed up with new investigations and soon began reporting more signals. Over time, with better radio telescopes, they found that some radio sources appeared as paired patches, one on either side of a tiny dot. They called these sources "radio galaxies." They also discovered other, more starlike sources—intense dots of radio energy without patches. How strange. What could these quasars (short for "quasi-stellar radio sources") be? Were they related to the radio galaxies?

According to the excerpt, how did astronomers use Reber’s findings to add to the knowledge of black holes?

Astronomers improved on Reber’s radio telescope and discovered the sources of the radio energy signals he mapped.
Astronomers used Reber’s radio telescope and renamed his discoveries “radio galaxies” and “quasars.”
Astronomers improved on Reber’s radio telescope and made new discoveries to prove his findings were wrong.
Astronomers used Reber’s maps of the signals from the space to locate radio galaxies.