Questions that require response
In the test editor you can make some or all questions Required. By doing so, you basically prevent people from moving to another page without responding to the questions that require responses.
If you don’t make a question Required, the user can leave the question blank.
The questions however, may have their own internal rules that determine what a valid response is. For example, let’s think of a multiple choice question that requires the user to select at least 2 options.
This rule will only apply when the user is answering to the question. The questions’s internal validation rules do not apply if the user leaves the question blank.
Only when the user is answering a question are the question’s internal validation rules applied.
Even though the question settings enforces the user to select at least 2 options, if the question is not made Required inside the test editor, the user can still leave this question blank.
So if you want to require the user to respond AND to pick at least 2 options, you must both make the question required and set the question settings so that it requires at least 2 options to be selected.