(a) Except as provided by Subsection (c), if a member dies before retirement, the amount of the member's accumulated contributions is payable as a lump-sum death benefit.
(b) The benefit provided by this section is payable to a person designated by the member in a signed document filed with the board of trustees. If a member does not designate a beneficiary, the benefit is payable to the member's estate.
(c) A death benefit may not be paid under this section if, at the time of death, the member was eligible to select a death benefit annuity under Section 839.301.