Answer:
a. Interest Expense
Explanation:
Only the Interest Expense would be increased by the coupon payment transaction.
Coupon payment includes interest payment and repayment of the Principle or Capital amount.
The entry for coupon payment is :'
Debit : Interest expense
Debit : Bond Payable
Credit : Cash
While the Cash- Asset and the Bond Payable- Liability are decreasing, only the Interest expense is increasing.