Final answer:
In 'Las Meninas' by Velázquez, the mirror on the back wall reflects the upper bodies of King Philip IV and Queen Mariana of Spain, who seem to stand in the viewer's perspective.
Step-by-step explanation:
In Velázquez's celebrated work Las Meninas, the individuals visible in the mirror on the back wall are King Philip IV and Queen Mariana of Spain. The mirror captures their upper bodies, which suggest that they are standing where the viewer would typically stand, looking into the art studio. Some art scholars believe that their reflection might be cast from the painting that Velázquez is shown working on within the scene itself. Las Meninas is renowned for its intricate composition that plays with perception and the blending of reality and illusion, engaging the viewer in a visual dialogue with the figures in the space, including the royal couple reflected in the mirror.