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: Pharmacology
All of the following drugs cause tachycardia except? 
Select and explain. 
A. Amphetamine, B. Nifedipine, C. Theophylline, D. Clonidine
D: Clonidine
Answer: D: Clonidine 
Explanation: Clonidine is α2 agonist and decreases the central sympathetic outflow. It decreases blood pressure as well as heart rate.