Which of the following characters can be combined with a separator string in order to read from the current input source until the separator string, which is on a separate line and without any trailin

The << operator begins a heredoc block, which redirects input from the shell script itself rather than a file. The shell reads lines until it encounters the delimiter string on a line by itself with no leading or trailing whitespace. For example, 'cat << EOF' collects all lines until a line containing only 'EOF' is reached.

<| is not a valid shell operator for any input redirection or heredoc purpose.

!< is not a valid shell operator - the ! character in shell is used for history expansion, not input redirection.

&< is not a valid shell operator for reading until a separator string.