This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Medicine
[{'content': 'Most common anterior mediastinal tumour is \nSelect and explain. \nA. Thymoma, B. Neurogenic tumor, C. Lymphoma, D. Teratoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Thymoma): {2181- H 18th edition)MEDIASTINAL MASSESAnterior mediastinumThymoma (Most common)***LymphomaTeratomatous neoplasmsThyroid massesMiddle mediastinum- Vascular masses (Most common)**- Lymph node enlargement from metastasis or granulomatous disease- Pleuropericardial and bronchogenic cystsPosterior mediastinum- Neurogenic tumours (Most common)**- Meningoceles, meningomyelocele- Gastroenteric cysts- Esophageal diverticula* Investigation of choice - CT-scan* Definite diagnosis - Mediastinoscopy or anterior mediastinotomy', 'role': 'assistant'}]