In making the demonstration required under subparagraph (A), the designated State unit shall explore the individual’s abilities, capabilities, and capacity to perform in work situations, through the use of trial work experiences, as described in section
705
(2)(D) of this title, with appropriate supports provided through the designated State unit, except under limited circumstances when an individual cannot take advantage of such experiences. Such experiences shall be of sufficient variety and over a sufficient period of time to determine the eligibility of the individual or to determine the existence of clear and convincing evidence that the individual is incapable of benefiting in terms of an employment outcome from vocational rehabilitation services due to the severity of the disability of the individual.