Which of the following is an example of an illusion?

An illusion refers to a misperception of a real external stimulus, meaning that the individual sees something that is there, but interprets it incorrectly. The correct choice is based on the notion that the individual misinterprets a familiar object or concept—in this case, a clock—believing it is something threatening, such as a bomb. This misinterpretation involves an existing object (the clock), leading to a distorted perception of its true nature.

In contrast, the other options illustrate concepts that do not align with classical definitions of illusion. Option A describes a visual hallucination, as the individual perceives a snake that is not actually present. Option C represents auditory hallucinations, where an individual hears voices that do not exist in reality. Option D involves a belief in mind reading, which is related to delusional thinking rather than a misperception of an actual object. Through this understanding, it becomes clear why the chosen response is recognized as an example of an illusion.