This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
A patient, Sunder is admitted to the emergency with severe bradycardia following drug overdose. The concerned drug was being taken for hypeension. When of the following cannot be the drug? 
Select and explain. 
A. Clonidine, B. Hydralazine, C. Propanolol, D. Reserpine
B: Hydralazine
Answer: B: Hydralazine 
Explanation: (Ref: KDT 6/e p547) It is a vasodilator and can result in reflex tachycardia. All other drugs listed in the question (clonidine, propanolol, reserpine) decrease the activity of sympathetic system and can result in bradycardia.