Illusion is -
Ans is 'b' i.e. Alteration of perception of one's reality o Altered perception of real object - Illusiono False perception without external stimulus - Hallucination.Illusiono Illusions are altered perception in which a real external object is combined with imagery to produce false internal percept. In simple words, illusion is misinterpretation of an actual sensory input. For example:-i) Hearing once name in a train whistle:- Train whistle is a real external stimulus, which is perceived as once name (false internal percept).ii) Mistaking a stick or rope for snake in dark room:- Stick is a real external object, which is perceived falsely as snake.In illusion:-i) Sensory input is in external atmosphere.ii) Percept is in internal atmosphere (inner subjective space, i.e., inside the mind).o Illusions are most commonly seen in delirium.
Feeling of familiarity with unfamiliar thing
Altered perception of real object
Belief in something even though the same is proved false
Perception occurring without external stimulation