A、A contractual arrangement. B、A counterpart. C、Many types of risks. D、Credit risk. D他们在谈论银行所面临的风险，女士说“The major type of risks

M: The paper money required little effort to carry. If you need large amount of money, you can use a check or credit card to make the payment.
W: This nature of money is called portability and it provides convenience in settling transactions.
Q: What does the word portability mean?

M: Can you give an example of types of risks Banks face?
W: Yes. The major type of risks is called credit risk. It means a counterpart fails to perform according to a contractual arrangement.
Q: What are they talking about?