Explanation: Aquadag is a conductive graphite coating applied to the inside of the Cathode Ray Tube (CRT) funnel, typically connected to a high positive voltage. This coating serves several vital functions in the operation of the CRT: 1. **Acts as a second anode (B):** The positive potential on the aquadag accelerates the primary electron beam towards the screen after it leaves the electron gun. This additional acceleration contributes to the beam's velocity, increasing the brightness and clarity of the displayed image, and assists in beam focusing. 2. **Attracts secondary emissions (C):** When the high-velocity electron beam strikes the phosphor screen, it knocks out secondary electrons from the screen material. If these secondary electrons were allowed to accumulate, they would create a negative charge buildup that repels the primary beam, degrading the image. The positive aquadag coating attracts and collects these secondary electrons, maintaining screen neutrality and ensuring stable image production. 3. **Protects from strong electric fields (A):** The conductive aquadag coating provides electrostatic shielding for the electron beam as it travels towards the screen. By maintaining a stable internal electric field and preventing charge accumulation on the glass envelope, it protects the sensitive electron beam from external electric fields that could cause unwanted deflection or distortion. Therefore, all the listed purposes contribute to the proper and efficient operation of a Cathode Ray Tube.