Final answer:
To balance the transaction where an asset account is debited for $500 and a revenue account is credited for $1,000, the correct action is to debit a shareholders' equity account for $500.
Step-by-step explanation:
The question involves a situation where an accountant has debited an asset account for $500 and credited a revenue account for $1,000. To ensure the transaction is accurately recorded and balanced as per the double-entry accounting system, an additional entry needs to be made.
The correct action to complete this recording would be option d: debit a shareholders' equity account for $500. This additional debit entry balances the overall transaction, keeping in line with the accounting equation: Assets = Liabilities + Shareholders' Equity.