The correct answer is: A and B.
The command cat *ch will display all files whose names start with the letter “ch”. This includes the files “patch” and “catch”. The file “.ch” is a hidden file, and will not be displayed by this command.
A hidden file is a file whose name begins with a dot (.). Hidden files are typically used to store system configuration information or user preferences. They are not normally displayed by default, but can be shown by using the ls -a command.
The cat command is used to display the contents of a file. The * character is a wildcard character that matches any number of characters. So, the command cat *ch will display the contents of all files whose names start with the letter “ch”.
In this case, the files “patch” and “catch” match the wildcard pattern, so their contents will be displayed. The file “.ch” does not match the wildcard pattern, so it will not be displayed.