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 H1 blocker has high anticholinergic activity : 
Select and explain. 
A. Cetirizine, B. Chlorpheniramine, C. Fexofenadine, D. Astemizole
B: Chlorpheniramine
Answer: B: Chlorpheniramine 
Explanation: None