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 β1 selective blocker is used in glaucoma: 
Select and explain. 
A. Levobunolol, B. Timolol, C. Betaxolol, D. Carteolol
C: Betaxolol
Answer: C: Betaxolol 
Explanation: None