Answer:
Option (C)
Explanation:
When J.J Thompson was performing an experiment with the cathode ray tube, he noticed that numerous rays or particles were released from the cathode (negatively charged) placing it at one end of the tube. And this group of rays moves towards the anode (positively charged) placing it on the other end. This negatively charged particles emitted from the cathode are known as the electrons.
From this, the electrons were discovered and were furthered studied by the scientists about their characteristics and behaviour.
Hence, the electrons came into picture after the discovery of vacuum tube.
Thus, the correct answer is option (C)
