《金匮要略》论历节病的成因是（）。

A.外感风寒湿之气

B.肝肾亏虚，筋骨失养

C.肝肾亏虚，风寒湿侵

D.肝肾不足，寒伤骨髓

E.阳气亏虚，血行不利

In relation to the Securities Law of China:

(d) explain the situation in which the underwriting with best efforts shall be deemed as a failure, and explain the statutory obligations of the issuer. (4 marks)