This subchapter applies only to eligible survivors of:
(1) an individual listed in Section 615.003(1), (6), or (7);
(2) an individual listed in Section 615.003(10) or (11) who is employed by a political subdivision of the state; or
(3) an individual who is:
(A) described by Section 615.003(15); and
(B) employed as a trainee for a position otherwise described by this section.