The purpose of control accounts is to keep the general ledger free of details yet fully accurate in order to prepare financial statements and other financial reports. Subsidiary ledgers contains the details of all the individual accounts and transaction activity. Since these are amounts owed to creditors, we may eliminate B & C for accounts receivable. Next, because the question asks for a controlling account, we may eliminate D which discusses a subsidiary account. A subsidiary account, by definition, is not a controlling account.