Answer:
b. debit to Accounts Receivable and credit to Sales Discount Forfeited for $120
Explanation:
The last payment of $12,000 it's without discount because was not made within the 10 days, so it's necessary to Debit Cash by $12,000 and reverse the accrual for the remaining $120 discount offered not applied.
The it's necessary to record this entry:
b. debit to Accounts Receivable and credit to Sales Discount Forfeited for $120