The htpasswd command is used to create and update user files for basic authentication of HTTP users. The command has several options, but the most relevant ones for this question are:

-c: This option creates a new file and overwrites it if it already exists. This is not suitable for changing the password of existing users, as it would erase the previous data.

-n: This option displays the results on standard output rather than updating a file. This is useful for generating password records for other types of data stores, but not for modifying an existing file.

-D: This option deletes the specified user from the file. This is not what the question asks for, as it wants to change the password, not remove the user.

-b: This option uses batch mode, which means getting the password from the command line rather than prompting for it. This option is not mentioned in the question, and it is not recommended for security reasons.

Therefore, the correct option is B, which uses the default syntax of htpasswd to change the password of an existing user in the specified file. The command will prompt for the new password and update the file accordingly.

References:

htpasswd - Manage user files for basic authentication

How to Create and Use .htpasswd

Unlocking htpasswd in Linux: Comprehensive Guide with Examples