预防地方性甲状腺肿最方便、可靠的措施是（）

A.碘化食糖

B.投碘化剂

C.碘化食盐或食油

D.碘化水质

E.移民

Which of the following statements about debt securities is most likely correct（）

A. A collateralized mortgage obligation is a derivative of a passthrough security with a payment structure that redistributes risk among investors in various tranches.

B. Insured bonds are bonds collateralized by an escrow of securities guaranteed by the U. S. government.

C. Tax-backed municipal bonds are supported through revenues generated from projects that are funded in whole or in part with the proceeds of the original bond issue.