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 drug is not used in the treatment of bronchial asthma : 
Select and explain. 
A. β2 agonists, B. Corticosteroids, C. Cholinesterase inhibitors, D. Phosphodiesterase inhibitors
C: Cholinesterase inhibitors
Answer: C: Cholinesterase inhibitors 
Explanation: None