The correct answer is: B. Rectangular
A CRO (Cathode Ray Oscilloscope) is an electronic instrument that is used to display waveforms. It consists of a cathode ray tube (CRT), which is a vacuum tube that contains an electron gun, a deflection system, and a phosphor screen. The electron gun emits a beam of electrons, which is then deflected by the deflection system to create an image on the phosphor screen. The waveform to be displayed is applied to the horizontal plates of the CRO, which causes the electron beam to be deflected horizontally. The vertical plates of the CRO are used to control the intensity of the electron beam, which determines the brightness of the image on the screen.
A sawtooth voltage is a type of voltage that has a linear increase followed by a linear decrease. This type of voltage is often used to sweep the electron beam across the screen of a CRO. However, it is not the type of voltage that is used to display the signal pattern. The signal pattern is displayed by applying a rectangular voltage to the horizontal plates of the CRO. A rectangular voltage is a type of voltage that has a constant amplitude and a constant frequency. This type of voltage is ideal for displaying waveforms because it produces a clear and sharp image on the screen.
A sinusoidal voltage is a type of voltage that has a sine wave waveform. This type of voltage is often used in AC power circuits. However, it is not the type of voltage that is used to display the signal pattern. The signal pattern is displayed by applying a rectangular voltage to the horizontal plates of the CRO.
None of the above is not the correct answer.