Correct Answer: Cathode ray tube

Solution : The correct option is a Cathode ray tube .

The sealed glass vacuum tube you are describing is commonly known as a Cathode Ray Tube (CRT). In a CRT, an electron beam is generated at the cathode and is focused using electromagnetic fields as it travels toward the phosphor-coated glass screen. When the electron beam strikes the phosphor coating, it causes the emission of light, which forms the images on the screen.