What are cathode rays?

 What are cathode rays?

1. A beam of electrons emitted from the anode of a high-vacuum tube.
2. A beam of electrons emitted from the cathode of a low-vacuum tube.
3. A beam of electrons emitted from the cathode of a high-vacuum tube.
4. a beam of electrons emitted from the anode of a low-vacuum tube.

THE CORRECT ANSWER IS: A beam of electrons emitted from the cathode of a high-vacuum tube.