What are cathode rays made of according to J. J. Thomson?

Thomson made the conclusion that the cathode ray is composed of negatively charged particles which were later named electrons.

The British physicist, J. J. Thomson performed a cathode ray tube experiment which led to the discovery of electrons.

Let's talk about cathode ray tubes and the cathode rays they emit: - \s- J.J. Thomson, a physicist, started using cathode ray tubes in his experiment in the late 19th century. These are the glass tubes that are sealed and where the majority of the air has been removed. A stream of particles flows from the cathode (the negatively charged electrode) to the anode when a high voltage is supplied between two electrodes at one end of the tube (the positive charged electrode).

Because the particle beam, also known as the "cathode ray," emanates from the cathode, these tubes are known as cathode ray tubes. A substance like phosphors can be painted onto the far end of the tube, past the anode, to detect this cathode ray. The phosphors ignite or emit light when the cathode ray emerges. J. J. Thomson surrounded the cathode ray with two electric plates that were charged in opposition to examine the characteristics of the particles. According to his observation, the cathode ray was made up of negatively charged particles since it was deflected away from the negatively charged electric plate and towards the positively charged plate.

Thomson came to the conclusion that the cathode ray is made up of electrons, which are negatively charged particles.

Hence option (C) is correct.