Final answer:
The correct answer is a) Invoice, which is compared with internal documents in a voucher system to ensure accurate recording of purchases in accounting records, as part of internal controls.
Step-by-step explanation:
The supplier invoice is compared to the internally generated documents of the voucher system to ensure the quantity and costs agree with what has been ordered and received. If all reconciles, the accounting department will record the purchase in the accounting records. The correct answer is a) Invoice. In the process of accounts payable, the invoice is the bill sent by the supplier and contains details such as quantity of goods, prices, terms of sale, etc. It is important for businesses to carefully check the supplier's invoice against the purchase order and the receiving report (packing slip) as a part of their internal control procedures.