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
Catecholamine action on α–receptors causes: 
Select and explain. 
A. Increased atrial contraction, B. Increased heart rate, C. Detrusor relaxation, D. Gastrointestinal sphincter contraction
D: Gastrointestinal sphincter contraction
Answer: D: Gastrointestinal sphincter contraction 
Explanation: None