Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

An interest rate swap is a derivative contract in which:
Option A:two parties agree to exchange a series of cash flows.
Option B:the credit seller provides protection to the credit buyer.
Option C:the buyer has the right to purchase the underlying from the seller.

Answer: A