Which of the Following Best Explains a 'Purchase Order Requisition

Which of the following best explains a 'Purchase order requisition'? 

A)  A document that is used by the buyer in which they agree to perform according to the order. 
B)  A description of internal customer requirements for goods and/or services needed to be obtained from suppliers. 
C)  A description of external customer requirements for goods and/or services needed to be obtained from suppliers, which will serve as the basis for the purchase order. 
D)  A description of internal customer requirements for goods and/or services needed to be obtained from suppliers, which will serve as the basis for the purchase order.