This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
A patient of schizophrenia was staed on haloperidol 5 mg. Next day, he presented with uprolling of eyes. Complete neurological examination revealed no spasticity or any other abnormality. Visual acuity and ophthalmoscopic findings are normal. Most likely diagnosis is : 
Select and explain. 
A. Akathisia, B. Acute dystonia, C. Seizure, D. Tardive dyskinesia
B: Acute dystonia
Answer: B: Acute dystonia 
Explanation: Acute muscular dystonia is the earliest appearing extrapyramidal symptom caused by antipsychotic drugs like haloperidol. REF: HARRISONS 20TH ED.