Final answer:
When a firm writes a check, there is an immediate decrease in the balance in the firm's books or ledger, but no immediate change in the bank balance.
Step-by-step explanation:
The correct choice is d) Book; bank.
When a firm writes a check, it decreases its balance immediately. This decrease is reflected in the firm's books or ledger.
On the other hand, there is no immediate change in the bank balance when a firm writes a check. The bank will process the check and decrease the firm's balance in its ledger.