This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Anatomy
The most commonest site of bleeding in haemoptysis is 
Select and explain. 
A. Tracheobronchial tree, B. Pulmonary parenchyma, C. Pleural disease, D. All the above
A: Tracheobronchial tree
Answer: A: Tracheobronchial tree 
Explanation: Ref Harrison 19 th ed/pg 1793 The most common source of bleeding in massive hemopthaemo are the bronchial aeries which are pa of the high pressure systemic circulation . In bronchitis, bronchiectasis or with endobronchial tumors. Ref Harrison 19th edition pg 1793