; (B) an adult person to whom the individual stands in loco parentis; or (C) any other adult person— (i) living in the household of the individual at the time of the death of the individual; and (ii) related to the individual by blood or marriage. (3) The term registered individual means an individual registered with the registry under subsection (a). 4. Determination of presumptions of service connection for illnesses associated with K2 exposure (a) In general (1) Determination required Not later than 60 days after the date on which the Secretary of Veterans Affairs receives the results of a covered study, the Secretary shall make a determination whether a positive association exists between— (A) the exposure of humans to toxic substances at Karshi Khanabad Air Base, Uzbekistan, at any time during the period beginning October 1, 2001, and ending December 31, 2005; and (B) the occurrence of a diagnosed illness in humans. (2) Bases of determination In making a determination under paragraph (1), the Secretary shall consider— (A) whether the evidence is statistically significant, capable of replication, and able to withstand peer review demonstrating that there is positive association between the exposure and the occurrence of a diagnosed illness; (B) the results of a covered study; and (C) all other sound medical and scientific evidence available to the Secretary. (3) Presumption If the Secretary determines that a positive association exists between exposure and a diagnosed illness pursuant to paragraph (1), the Secretary shall prescribe regulations providing that— (A) a presumption of service connection is warranted for the illness covered by that determination if the illness first becomes manifest within the period, if any, prescribed in such regulations in a covered veteran