Correct option is C
A Cathode Ray Tube (CRT) is not a solid-state device. It is a vacuum tube that displays images by using electron beams to excite phosphorescent screens. CRT technology was widely used in older television and computer monitors but has largely been replaced by solid-state devices like LCD, LED, and plasma screens. Solid-state devices refer to electronic devices made from solid materials where electrical conduction occurs through the movement of electrons in a solid medium (such as a semiconductor). Examples include FET (Field Effect Transistor), LED (Light Emitting Diode), and Tunnel Diode, which are widely used in modern electronics for switching, lighting, and amplification functions. CRT, being a vacuum tube, does not belong to the solid-state category.
