对于以下二叉树，进行中序遍历的结果为：

A．ABCDEF

B．DBEACF

C．ABDECF

D．DEBFCA

Which of the following statements concerning arbitrage-free bond prices is FALSE（）

A. The riskier the bond, the greater is its credit spread.

B. It is not possible to strip coupons from U. S. Treasuries and resell them.

C. The determination of spot rates is usually done using risk-free securities.