Final answer:
Shannon perceives one object in the painting as a 2-dimensional circle and another object as a 3-dimensional sphere. The monocular cues that can account for this effect are linear perspective and relative size.
Step-by-step explanation:
An example of a monocular cue that can account for Shannon perceiving one object as a 2-dimensional circle and another object as a 3-dimensional sphere in the painting is linear perspective. Linear perspective refers to the fact that we perceive depth when we see two parallel lines that seem to converge in an image. Another monocular cue that can contribute to this effect is relative size. If Shannon perceives the circle as smaller than the sphere, it can indicate that the circle is further away and therefore appears 2-dimensional. However, without a specific visual context, it is difficult to determine which exact cues are at play.