Ans. is 'b' i.e., Ophthalmoplegia Response to thiamine treatment in Wernicke's encephalopathy Ocular symptoms :- Earliest to respond, ophthalmoplegia (ocular palsies) improves within hours of thiamine administration. However, horizontal nystagmus may persist. Ataxia :- Ataxia responds more slowly than ocular palsies and half the patients recover incompletely with a residual ataxia. Encephalopathy :- Confusion and other CNS symptoms improve more slowly. As the symptoms of encephalopathy improve, Korsakoff's syndrome may become apparent in some patients