The correct answer is: C. 63 characters.
A path name is a string of characters that identifies a file or directory on a computer system. It consists of a drive letter, followed by a colon (:), followed by the path to the file or directory. The path to a file or directory can be relative or absolute. A relative path is a path that is relative to the current working directory. An absolute path is a path that is complete and does not depend on the current working directory.
The maximum length of a path name is 63 characters. This includes the drive letter, colon, and any slashes (/) or backslashes () that are used in the path. The name of the file or directory itself cannot be more than 255 characters long.
Option A is incorrect because it is the maximum length of a file name, not a path name. Option B is incorrect because it is the maximum length of a drive letter. Option D is incorrect because it is the maximum length of a directory name.