问题如下：
The notional principal of a swap is:
选项：
A.not exchanged in the case of an interest rate swap.
B.a fixed amount whenever it is matched with a loan.
C.equal to the amount owed by one swap party to the other.
解释：
A is correct. The notional principal of a swap is not exchanged in the case of an interest rate swap.
B is incorrect because an amortizing loan will be matched with a swap with a pre- specified declining (not fixed) notional principal that matches the loan balance.
C is incorrect because the notional principal is equal to the loan balance. Although the loan has an actual balance (the amount owed by the borrower to the creditor), the swap does not have such a balance owed by one swap party to the other.
这道题应该怎么理解？
