The "uncertainty" mentioned of the passage refers to the A. doubt that owners of works of art often harbor over whether individuals have a moral right to possess great art B. concern that owners of works of art often have that their possession of such objects may be legally challenged at any time C. questions that owners of works of art often have concerning the correct identification of the age and origin of their objects D. disputes that often arise between cultural institutions vying for the opportunity to purchase a work of art E. apprehension that owners of works of art often feel concerning the possibility that their objects may be damaged or stolen from them