This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
A patient on antipsychotics was admitted with complaints of muscle rigidity, fever and tachycardia. Investigations showed increase in WBC counts and increase in creatinine phosphokinase levels. Drug of choice for this patient is : 
Select and explain. 
A. Paracetamol + IV Fluids, B. Dantrolene, C. Neostigmine, D. Paracetamol + Penicillin
B: Dantrolene
Answer: B: Dantrolene 
Explanation: The above symptoms suggests of "Neuroleptic malignant syndrome", a fatal side effect of antipsychotics. It is treated using Dantrolene which is a directly acting muscle relaxant that inhibits Ryanoudine receptors and prevent release of calcium from sarcoplasmic reticulum.