Why Are the Regular GNMA Pass-Throughs Not Very Attractive to Insurance

Why are the regular GNMA pass-throughs not very attractive to insurance companies and pension funds seeking long-term duration assets to match their long-term duration liabilities?

A) Because of their short expected duration.
B) Because these bonds have the shortest average life with a maximum of prepayment protection.
C) Because they are zero coupon bonds and hence carry maximum amount of risk.
D) Because of their failures to offer prepayment protection.
E) Bondholders receive the promised coupon and principal payments but are not entitled to accrued interest payments.