Cathode Rays consist of _____.

Electrons

The correct answer is option 3. electrons.

Cathode rays consist of Electrons. Cathode rays are streams of electrons observed in vacuum tubes when high voltage is applied between electrodes. These electrons are emitted from the cathode (negative electrode) and accelerated toward the anode (positive electrode). They were first discovered by J.J. Thomson in the late 19th century and were later identified as streams of negatively charged particles, which we now know as electrons.