The correct answer is B. 3.5″.
A floppy disk is a data storage medium that was widely used from the 1970s to the early 2000s. It is a small, rectangular disk made of flexible magnetic material that is enclosed in a hard plastic case. Floppy disks were used to store and transfer data between computers.
The most common type of floppy disk is the 3.5-inch floppy disk. It was introduced in 1982 by IBM and quickly became the standard floppy disk format. 3.5-inch floppy disks can store up to 1.44 megabytes of data.
Other types of floppy disks include the 5.25-inch floppy disk, which was introduced in 1976 and could store up to 360 kilobytes of data, and the 8-inch floppy disk, which was introduced in 1971 and could store up to 1.2 megabytes of data.
Floppy disks are no longer widely used, as they have been replaced by newer storage media such as USB drives and CDs. However, they are still used in some specialized applications, such as embedded systems.