What subatomic particle was discovered with the use of a cathode-ray tube

The correct answer is: Electron

Explanation:

Electron (e⁻) is the negatively charged subatomic particle that has an electric charge of - 1e (-1.6022 * 10⁻¹⁹ C). It was discovered by the English physicist, Sir Joseph John Thomson (J. J. Thomson) in the year 1897 by the cathode ray experiment.

In the cathode ray experiment, Sir Joseph John Thomson used the cathode ray tubes to conclude the presence of negatively charged small subatomic particle, known as electrons, in all atoms.