This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lung, Subject name: Surgery
Foreign body the common passage is 
Select and explain. 
A. Right main bronchus, B. Left main bronchus, C. Bronchioles, D. Alveoli
A: Right main bronchus
Answer: A: Right main bronchus 
Explanation: A. i.e. (Right main bronchus) (297 -Dhingra 4th)Foreign bodies* Children - seeds, beans, tiny toys* Adult - meat is the most common cause of obstruction* Most common route by which a foreign body enters the nose is the anterior nares (179 - Maqbool 11th)* Commonest site of foreign bodies of food passage is at or just below the cricopharyngeal sphincter. (311 - Dhingra 4th)Most foreign bodies enter the right bronchus because it is wider and more in line with tracheal lumen causes - atelectasis or check valve obstruction* Double density sign of chest x-ray is a feature of left atrial dilatation*** Fish bone, chicken bone, needle or a denture may lodge in the pyriform fossa