This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
All of the following statements about clonidine are true EXCEPT 
Select and explain. 
A. It is an alpha adrenergic agonist, B. It can cause dry mouth as an adverse effect, C. Prazosin completely antagonizes its action, D. It inhibits sympathetic outflow.
C: Prazosin completely antagonizes its action
Answer: C: Prazosin completely antagonizes its action 
Explanation: Clonidine is a central sympatholytic. It is an agonist to alpha2 receptors. But prazosin is a selective alpha1 blocker selective alpha 2 blocker is yohimbine Clonidine can cause dryness of mouth, nose, and eyes due to central sympatholytic action. (REF. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D TRIPATHI-6th edition. Page No.545,546)