The correct answer is: B. ls chap[124]
The command ls lists the contents of the current directory. The asterisk (*) is a wildcard character that matches any number of characters. So, the command ls chap* will list all files and directories whose names start with “chap”. The command ls chap[124] will list all files and directories whose names start with “chap” and have one of the digits 1, 2, or 4 in the second position. However, this command will not list the file “chap03”.
The command ls -x chap0[124] is similar to the command ls chap[124], but it will also list hidden files. Hidden files are files whose names start with a dot (.). The file “chap03” is a hidden file, so it will be listed by the command ls -x chap0[124], but it will not be listed by the command ls chap[124].
The command ls chap0[124] is not used to list the files chap01, chap02, and chap04.