选项
A.
A.afixed level of income for the life of the owner.
B.
B.avariable level of income for owners on a fixed income.
C.
C.afixed or variable income stream at the option of the owner.
D.
D.afixed stream of income or a stream of income that is determinedaccording to a specifiedformula forthe life of the security.
正确答案：D