Cathode ray tube experiment provided the first evidence of x-rays or subatomic particle or magnetic field or electric field?

Thomson conducted the experiment.

The cathode ray tube experiment provided the first evidence for subatomic particles or, more specifically, electrons.

For a more in-depth explanation: when Thomson conducted this experiment, he set up the cathode ray tube, which sent a beam across the tube (which we know now is made of electrons, but at the time no one knew what an electron was or how they related to electricity). He then brought a magnet near the tube and found that it repelled the beam in the opposite direction, in the same way that a wire carrying a current was deflected by a magnet.Therefore, he concluded that whatever particle was part of the beam, it must be negatively charged.

Moreover, Thomson did this experiment with different metals at the cathode. We know that any metal is going to emit electrons to create the ray, but again, back then they didn't know what electrons were. No one had yet managed to disprove the theory that atoms were indivisible. But by using the different metals and getting the same results, Thomson's theory suggested that all atoms had the exact same negatively charged particles inside them, which is exactly what we know today.