How do I set the correct answer for a text field input.

Hi,
When you create Question, choose 'Text field' as Answer Type and set Answer to match user's input. (See attachment)

How do i set the correct answer for a text field input.
ie for questions that I do not want to be multiple choice but have a single correct answer.
The ability to identify the answer only seems to be available when there are options entered (drop down, radio, checkbox etc)
The documentation does not indicate how to enter questions and answers (I searched the documentation for 'text field' and 'answer'