Concept:A statement of account is a summary of transactions between a seller and a customer.
Explanation:This document lists all sales, payments, and other changes made during a specific period.
It shows the beginning balance, each transaction, and the final amount owed.
The statement helps both parties know whether the customer still owes money or has paid in full.
Other documents, such as a proforma invoice, differ because they are not used for recording past transactions.
Answer:Statement of account (Option A).