Final answer:
To get help about the 'cp' command, use 'man cp', which displays the user manual for the command, detailing its functions, options, and example usage.
Step-by-step explanation:
To get help about the command cp in a UNIX-based system, option 2) man cp is the correct choice. The man command stands for 'manual' and is used to display the user manual of any command that we can run on the terminal. When you enter man cp, it will show you all the information about the cp command, including its description, options, and usage examples.
If you are in a shell where the man pages are not available, you can sometimes use --help appended to the command itself (e.g., cp --help) to get a brief overview of the command options and usage.