Which of the following does NOT constitute rebating? 
A. 30% of an agent's total "book" of business for the year is derived from a single source of controlled business. 
B. Waiving a fee or charge for a good customer. 
C. 60% of an agent's total "book" of business for the year is derived from sources of controlled business. 
D. Allowing a "discount" as filed with the Department of Insurance in the company's rating plan, for the simultaneous issue of two policies.