Invalid reply message

I have a practice on a page that consists of sentences that need to be answered in a correct or incorrect check box (you can choose any sentence- right or wrong).

I created a layer that, if no check box is checked, shows an invalid response message and the variable needs to answer the question sections.

I would like to create a condition that, if I have not answered all the question clauses, the answer will not be valid (meaning that the mark in each section is true or false)
How can I register such a condition?

3 Replies