grouping fields due to checked box

I work for a Michigan intermediate school district (ISD) and currently I am making HR forms fillable. I have a question in section 1 of the attached file that has 2 checkboxes the person must select 1 or the other. Question A. is only a checkbox, but if the person selects B., then follow-up questions must be completed. How do I add a condition to lock B. checkbox and questions, if A.? If B. is checked, how do I group the questions so the person completing the form completes the required fields for B.?