At the option of the State, any individual who—

(A) is 18 years of age or younger and qualifies as a disabled individual under section 1382c(a) of this title ;

(B) with respect to whom there has been a determination by the State that— (i) the individual requires a level of care provided in a hospital, nursing facility, or intermediate care facility for the mentally retarded, (ii) it is appropriate to provide such care for the individual outside such an institution, and (iii) the estimated amount which would be expended for medical assistance for the individual for such care outside an institution is not greater than the estimated amount which would otherwise be expended for medical assistance for the individual within an appropriate institution; and

(C) if the individual were in a medical institution, would be eligible for medical assistance under the State plan under this subchapter,

shall be deemed, for purposes of this subchapter only, to be an individual with respect to whom a supplemental security income payment, or State supplemental payment, respectively, is being paid under subchapter XVI.