Concept:A proforma invoice is a preliminary bill sent before goods are delivered, requesting payment in advance and politely refusing credit.
Explanation:When a buyer wants credit, the seller may send a proforma invoice instead of an ordinary invoice.
It states the details of the goods and asks the buyer to pay before shipment.
This acts as a polite way of refusing credit while still showing interest in the sale.
An advice note confirms dispatch of goods, a quotation lists prices, and an invoice demands payment after delivery.
Answer:Option C: proforma invoice.