This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardio thoracic surgery  , Subject name: Surgery
Most common tumor of anterior mediastimum is 
Select and explain. 
A. Thymoma, B. Lymphoma, C. Germ cell cumor, D. Thyroid tumors
A: Thymoma
Answer: A: Thymoma 
Explanation: Thymomas are the most common tumours of anterosuperior mediastinum in the adult,accounting for 25% of the total.They are most common in the 5th and 6th decades of life.Both sexes are equally affected.They vary in behaviour from benign to aggressively invasive.Diagnosis and treatment are best achieved by complete thymectomy.