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List I: Disorder	List II: Description
(a) Parkinson's Disease	(i) Movement disorder associated with cognitive deficits
(b) Huntington's Disease	(ii) Progressive motor disorder associated with severe dementia
(c) Alzheimer's Disease	(iii) Progressive decline in memory starting with selective forgetting
(d) Korsakoff Syndrome	(iv) A form of dementia which is caused by deficiency of vitamin Thiamine

Correct option is A

This matching accurately pairs neurological disorders with their clinical presentations. (a) Parkinson's Disease is a movement disorder (tremor, rigidity, bradykinesia) that is often accompanied by cognitive deficits including executive dysfunction and dementia (i), caused by dopaminergic neuron degeneration in the substantia nigra. (b) Huntington's Disease is a progressive motor disorder characterized by chorea (involuntary movements) associated with severe dementia and psychiatric symptoms (ii), resulting from CAG repeat expansion on chromosome 4. (c) Alzheimer's Disease involves progressive decline in memory beginning with selective forgetting (anterograde amnesia, episodic memory loss) (iii), caused by amyloid plaques and neurofibrillary tangles. (d) Korsakoff Syndrome is a form of dementia caused by vitamin B1 (Thiamine) deficiency (iv), typically seen in chronic alcoholism, featuring anterograde amnesia and confabulation. Option 3 correctly distinguishes these neuropsychological disorders.