On any tract not less than twenty acres in area, and where approved by the Board of Supervisors as a conditional use, a landowner or developer may be allowed to reduce the requirements of Section 503.B., under any or a combination of the following options in accordance with Article 20:

A. Standard Open Space Option;

B. Flexible Open Space Option;

C. Combination of Open Space Options. No tract may be used for more than one of the permitted open space options unless it can be demonstrated to the satisfaction of the Board of Supervisor's that development under each option shall individually comply with all the requirements of this Ordinance, and that their combination also shall conform with the purposes of this Section.