A registered separate account, any principal underwriter for such account, any dealer in contracts or units of interest or participations in such contracts issued by such account and any insurance company maintaining such account shall, with respect to any variable annuity contracts, units, or participations therein issued by such account, be exempted from section 22(d) to the extent necessary to permit the sale of such contracts, units or participations by such persons at prices which reflect variations in the sales load or in any administrative charge or other deductions from the purchase payments; Provided, however, That (a) the prospectus discloses as precisely as possible the amount of the variations and the circumstances, if any, in which such variations shall be available or describes the basis for such variations and the manner in which entitlement shall be determined, and (b) any such variations reflect differences in costs or services and are not unfairly discriminatory against any person.