The electrode connected to the negative terminal of the voltage source is called
Cathode
The explanation for the correct option:
Electrode: It is a solid electric conductor that carries electric current into non-metallic solids, liquids, gases, plasmas, or vacuums.
(A) Cathode: The electrode connected with the negative terminal of the battery is known as the cathode.
The explanation for the incorrect options:
(B) Anode: The electrode connected with the positive terminal of the battery is known as the anode.
(C) Diode: A diode is a two-terminal electronic component that conducts electricity primarily in one direction. It has high resistance on one end and low resistance on the other end.
(D) Cathode rays: It is the beam of electrons traveling from the negatively-charged cathode to the positively charged anode at the other end of the vacuum tube. These cathode rays travel in a straight-line path at high speed when a voltage difference is applied to the electrodes.
Thus, the correct option is option(A).