—Where's my watch? I can't find it anywhere.            

—It _     _ in your bag or under these books.              [ ]

A. might be              

B. must be            

C. mustn't be

记账式国债是由财政部面向个人投资者、通过无纸化方式发行的、以电子记账方式记录债权并可以上市和流通转让的债券。（）