Answer: a. appropriations exceed estimated revenues
Explanation:
A Budgetary Fund Balance is simply an account that Government agencies and Departments have to calculate the difference between expected inflows and Outflows for the period that a budget covers.
It is a temporary account with it's balance going to the General fund. If it is debited in the General fund then that means that Appropriations approved for the period are more than the revenues expected. The reverse is true.
