This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Failure, Subject name: Medicine
Most common primary lung cancer in children: 
Select and explain. 
A. Metastasis, B. Bronchial adenoma, C. Adenocarcinoma, D. Pulmonary blastoma
B: Bronchial adenoma
Answer: B: Bronchial adenoma 
Explanation: - The most common primary lung tumor is bronchial adenoma. - It includes bronchial carcinoid and adenoid cystic carcinoma. - Metastatic lesions are overall the most common forms of pulmonary malignancy in children.