Question

an imaginary perception such as seeing, hearing, or smelling something that does not exist in the external world is called a(n)
a. illusion
b. grouping
c. stroboscopic movement
d. muller - lyer illusion

Explanation:

A hallucination is an imaginary perception of seeing, hearing, or smelling something that doesn't exist in the external world. A illusion is a misinterpretation of a real - world stimulus, grouping is related to perceptual organization, stroboscopic movement is a type of apparent movement, and the Müller - Lyer illusion is a specific visual illusion.

Answer:

No correct option provided as the correct term is hallucination. But if we assume it's a mis - question and we have to choose from the given options, none of them are correct for the described phenomenon.