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
Which of the following effects of adrenaline would be blocked by phentolamine but NOT by propranolol ? 
Select and explain. 
A. Cardiac stimulation, B. Relaxation of bronchial smooth muscle, C. Relaxation of the uterus, D. Contraction of the radial smooth muscle in the iris
D: Contraction of the radial smooth muscle in the iris
Answer: D: Contraction of the radial smooth muscle in the iris 
Explanation: None