Ans. is 'a' i.e., Person is not responsible if he is not of a sound mind o According to Me Naughtcn's rule, a person is not responsible for his act, if has unsound mind at the time of act.o The criminal responsibility of an insane is judged as per the following rules :1) MC Naughten rule (legal test or right or wrong test):# Accused danieal MC Nauthten (probably suffering from paranoid schizophrenia and having persecutory delusions) shot Sir Peel's private secretory, Edward Drummond, mistaking him for the prime minister Sir Robert Peel. He was found not guilty on grounds of insanity. The answers given by panel of 14 judges to house of lords to clarify the legal position (on 19 june 1843) as known as MC Naughten rule.# It states that an accused person is not legally responsible, if it is clearly proved that at the time of commiting the crime, person was suffering from such a defect of reason from abnormality of mind that he didn't know the nature and quality of act he was doing or that what he was doing was wrong i.e. a person is not responsible if he is not of sound mind.# It is accepted in india as law of criminal responsibility and is embodied in section 84 IPC as - "nothing is an offence which is done by a person, who at the time of doing it, by reason of unsoundness of mind is incapable of knowing the nature of act, or that he is doing what is either wrong or contrary to law".# The primary defect is that the criteria for deciding insanity is purely intellectual (reason based). And there is no place for delusional beliefs, hallucinations, emotional and volitional factors and the ability of an individual to control the impulses. This is because the abnormality of mind (term used in this rule) is a legal and not a psychiatric concept and is concerned with the mind (i.e. reason, memory and understanding) not with the brain.# Clearly proved (term) means that the mental abnormality had a direct causal relation to the offence (i.e. it would not have occurred in absence of mental abnormality).# Crime consists of actus reus (i.e. guilty act) and mens rea (wrong intention). So if at the time of crime, the accused had the capacity to know that his act was wrong, he will be fully responsible, even if he was mentally ill, and unable to refrain from doing the act at that time.# If an accused commits a crime under the influence of delusion, he is j udged as if the delusionary facts were real. So if due to an insane delusion, a person kills a man in self defence (thinking that he is attempting to kill him or thinking that he is a wild animal) or as a part of job (thinking that he is a state executioner and has to execute the victim) he has no criminal responsibility and is exempt from punishment. But due to an insane delusion, if a person thinks that another person has caused a serious injury to his fortune and character and kills him, he becomes responsible as under the law no one can kill a person in revenge.2) Doctrine of partial responsbility# If a person is suffering from some weakness or aberration of mind (though not completely insane), he is only partially responsible for his actions, e.g. obsessional states or depressions.3) Durban rule# Accused is not responsible for the act, if his act resulted from mental disease or defect.4) Currens rule# A person is not responsible if at the time of committing the crime, he did not have the capacity to regulate his conduct according to the requirments of law, as a result of his mental disease or defect.5) American law institute test# Insane lacks the capacity to appreciate the wrongfulness of his conduct or to confirm to the requirements of law, therefore he is not responsible for crimes committed.6) Norwegion system# No defendent considered insane or unconscious at the time of offence, may be punished.