A systems administrator needs to append output of command to the contents of ls -lha /opt a test.txt file. Which of the following commands will accomplish this?

The `>` operator redirects the standard output of a command and overwrites the contents of the specified file if it already exists, rather than appending.

The `<` operator redirects the contents of a file as standard input to a command, which is the opposite of what is needed to append command output.

The `>>` operator redirects the standard output of a command and appends it to the end of the specified file. If the file `test.txt` does not exist, it will be created before the output is written.

The `<<` operator is used for a 'here document', providing multiple lines of input to a command until a specified delimiter is encountered, which is not applicable for appending command output.