Correct option is A
The main directory of a disk is called the
Root directory. It is the top-level directory in a file system from which all other directories and files branch out.
Root: Correct, as it refers to the top-level directory.
Sub: Incorrect, as it usually refers to directories that are within other directories.
Network: Incorrect, as it refers to a system of interconnected computers or devices, not a directory.
Folder: Although commonly used to refer to directories in general, it is not specifically the top-level directory.
Therefore, the correct answer is (a) Root.
