S$.99$ Prior to the enactment of the Illinois Human Rights Act, a small lakeside subdivision ratified a restrictive covenant that prevented conveyances or rentals to members of a certain religion that all the voting residents opposed. In this case,$\text{'}$

a$.$ The covenant is void.

b$.$ The covenant is legal since it preceded the IHRA.

c$.$ The covenant is legal but unenforceable.

d$.$ The covenant is legal since the Act grandfathers subdivision covenants.