Five cemeteries (Cemetery Group), within a six-mile radius of each other, followed a pattern of selling burial lots only on the condition that the buyer also purchase a grave marker from or through the cemetery as well as the services necessary to install the marker. The five cemeteries were all owned by the same group of investors and were the only cemeteries within that six-mile radius. Moore, a gravestone manufacturer, brought a private antitrust action again the Cemetery Group. The Group argued that the joint sale of lots and markers were necessary to retain neatness and aesthetic quality control of the cemetery grounds. Is this an illegal tying arrangement? Explain.