Which illusion or test was most difficult for you to perceive correctly? Why do you think this particular illusion was so challenging for you?

There are three main types of optical illusions including literal illusions, physiological illusions and cognitive illusions. All three types of illusions have one common thread. The perception of the image given to the brain doesn't measure up.

A misperception of a stimulus object, event, or experience, or a stimulus that gives rise to such a misperception or misconception; more generally any misleading, deceptive, or puzzling stimulus or the perceptual experience that it generates. See auditory illusion, tactile illusion, visual illusion.

-Objects can be hidden or blurred

-Objects look different from different viewpoints

-Image on the receptor is ambiguous

Movement of the observer can resolve ambiguity.

you didn't give any options but heres what i can tell you: an inference is likely to change based on additional observations. the latter is something that you have seen or sensed using your sensory organs while the former is like a conclusion out from what you have observed.

a chain link fence because there so tiny even my albino donkey can't get out