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
Which of the following treatment would be least effective for asystole? 
Select and explain. 
A. External pacemaker, B. Intravenous epinephrine, 10 ml. of 1:10,000, C. Intravenous calcium gluconate, 10 ml. of 10% solution, D. Intravenous atropine, 0.5 mg
C: Intravenous calcium gluconate, 10 ml. of 10% solution
Answer: C: Intravenous calcium gluconate, 10 ml. of 10% solution 
Explanation: The recommended treatment for asystole is the administration of atropine. If atropine is unsuccessful epinephrine is given. Ultimately cardiac pacing is necessary if atropine and epinephrine do not establish an adequate hea rate. Calcium has no clear role in treating asystole. Ref: harrisons text book of internal medicine, 20th ed.