The correct answer is D. All of the mentioned.
A command is a CLI command which does a specific task. For example, the ls command lists the contents of a directory. A flag is an option given to a command to activate a particular behavior. For example, the -l flag to the ls command lists the files in long format.
However, there are some commands that do not have any flags. For example, the pwd command prints the current working directory, and the cd command changes the current working directory. There are also some commands that have multiple flags. For example, the grep command can be used to search for a pattern in a file, and it has many different flags that control how the search is performed.
Therefore, the statement “There is one and only flag for every command in CLI” is incorrect.