The correct answer is 'noatime'. This mount option disables the updating of access times on files when they are read, which can improve performance, especially on frequently accessed filesystems. The 'relatime' option updates access times only if the previous access time was earlier than the current modify or change time. 'sync' and 'dirsync' are not directly related to file access time updates; 'sync' makes all writes synchronous, and 'dirsync' ensures directory changes are written synchronously, but neither disables the update of access times.