Choose the correct statement regarding the delusion:

The correct answer is Option (1) → Delusion is a false belief held on inadequate grounds

Option (1) Delusion is a false belief held on inadequate grounds — Correct. A delusion is a false belief that is firmly held on inadequate grounds. It is not affected by rational argument and has no basis in reality. It is one of the positive symptoms of schizophrenia; delusions of persecution are the most common.

Option (2) Delusion is a perception that occurs in the absence of external stimuli — Incorrect. This is the definition of a hallucination, a disorder of perception, not of belief. A person who hears voices when no one is speaking is hallucinating.

Option (3) Delusion involves disorganised speech — Incorrect. Disorganised thinking and speech are a separate positive symptom, called formal thought disorder: the person cannot think logically and speaks in peculiar ways, jumping from one topic to another. A delusion can be stated in perfectly clear speech.

Option (4) Delusion involves making odd grimaces and gestures — Incorrect. Odd grimaces and gestures are psychomotor symptoms of schizophrenia, which in extreme form become catatonia. They concern movement, not belief.