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 expectorant causes gastric irritation & reflex increase in bronchial gland secretions 
Select and explain. 
A. Ambroxol, B. Guaifenesin, C. Sodium cromoglycate, D. Fosaprepitant
B: Guaifenesin
Answer: B: Guaifenesin 
Explanation: Guaifenesin, hypertonic saline & ammonium cloride are the expectorants that cause gastric irritation and also reflexly increase bronchial gland secretions.