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 is the most potent 2nd generation antihistamine? 
Select and explain. 
A. Astemizole, B. Desloratadine, C. Promethozine, D. Fexofenadine
B: Desloratadine
Answer: B: Desloratadine 
Explanation: Desloratidine, metabolite of loratadine is the most potent 2nd generation antihistamine.