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
Combination use of beta blockers and calcium channel blockers cause: 
Select and explain. 
A. Heart block, B. Hypotension, C. Bradycardia, D. All of these
D: All of these
Answer: D: All of these 
Explanation: None