Able, an accounts payable supervisor for ABC Company, bought supplies for a company he owned on the side. Able entered vouchers in ABC Companys accounts payable system for the cost of the supplies. Checks were cut to pay for these unauthorized expenses during normal daily check runs. The goods ordered were drop-shipped to a location where Able could collect them. This is an example of:

a. A billing scheme

b. An expense reimbursement scheme

c. A commission scheme

d. An invoice kickback scheme