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
β-blockers with intrinsic sympathomimetic properties a) Propranolol b) Oxprenolol c) Pindolol d) Esmolol e) Butoxamine 
Select and explain. 
A. ab, B. ae, C. ad, D. bc
D: bc
Answer: D: bc 
Explanation: None