内外贸融易通项下可办理的保函业务不包括（）。

A.跟单信用证

B.涉外保函

C.国内保函

D.保付加签

For a given good or service, the marginal social benefit ( MSB and the marginal social cost (MSC) curves are least accurately described by which of the following（）

A. Producer surplus is determined by price and the MSC curve and consumer surplus is determined by price and the MSB curve.

B. The efficient allocation of resources occurs where the difference between the MSB and MSC curves is maximized.

C. The market demand curve is the same as the MSB curve, and the market supply curve is the same as the MSC curve.