The correct answer is: B. Bistable storage.
Bistable storage is a type of non-volatile memory that can be used to store data indefinitely without power. It is also known as halftone storage or mersh storage. Bistable storage is made up of two stable states, which can be represented by the values 0 and 1. The data is stored by changing the state of the bistable elements.
A. Variable persistence storage is a type of non-volatile memory that can be used to store data for a long period of time, but it is not as permanent as bistable storage. The data in variable persistence storage can be erased by applying a voltage to the memory cells.
C. Flat storage is a type of non-volatile memory that is used to store data on a flat surface. Flat storage is often used in printers and scanners.
D. CRT is a type of display device that uses a cathode ray tube to create an image on a screen. CRTs are no longer commonly used, but they were once the most common type of display device.