(1) A fractional share of the property determined by dividing the number one by the number of joint holders alive immediately before the death of the holder to whose death the disclaimer relates; or
(2) All of the property except that part of the value of the entire interest attributable to the contribution furnished by the disclaimant.
(b) A disclaimer under subsection (a) of this section takes effect as of the death of the holder of jointly held property to whose death the disclaimer relates.
(c) An interest in jointly held property with right of survivorship disclaimed by a surviving holder of the property passes as if the disclaimant predeceased the holder to whose death the disclaimer relates.