Concept:The fee charged by the post office for a postal order is a commission called poundage.
Explanation:A postal order has a printed value.
The post office charges a small fee for issuing it.
This fee is based on the value of the postal order.
This charge is officially known as poundage.
It is not interest, as no borrowing is involved.
It is not brokerage, which relates to buying and selling securities.
It is not premium, which is an insurance payment.
Answer:C. poundage