Which of the following transactions is posted to the nominal ledger?

The nominal ledger is used to record transactions related to revenues, expenses, gains, and losses. Therefore, the transaction that is posted to the nominal ledger is "discounts allowed to customers," as it is an expense account representing a reduction in the selling price of goods or services. The other transactions mentioned - cash paid by a customer, purchase of fixed asset for cash, and cash paid to suppliers - are all posted to other ledger accounts, such as the cash book, fixed asset register, and accounts payable ledger, respectively.