option, option button

In general, avoid talking about the UI. Instead, talk about what the customer needs to do. Refer to an option by its UI label only. If you must provide a descriptor, use option. Use the exact label text, including its capitalization, but don't capitalize the word option.

Avoid referring to the option button itself. Just discuss the option that it controls. When you must mention the button for clarity, use option button.

Examples
Select No header row.
When you select the Keep source formatting option, ....
For Paste options, select Keep text only.

In content for a technical audience, it's OK to use option instead of switch to refer to a command argument or compiler option, such as /b or /Za.

See also Describing interactions with UI, Formatting text in instructions