Concept:Subsidiary books are books of original entry where transactions are first recorded before posting to the ledger.Explanation:The sales day book records credit sales, and the purchases day book records credit purchases; both are subsidiary books.The general journal is also a subsidiary book used for entries that do not fit into other special journals.A trial balance is not a book of original entry.It is a statement prepared from ledger balances to check the arithmetical accuracy of accounts.Answer:D. trial balance