This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
A patient presents with mediastinal mass with sheets of epithelial cells giving arborizing pattern of reactivity on keratin, along with interspersed lymphoid cells. The most probable diagnosis is: 
Select and explain. 
A. Thymoma, B. Thymic carcinoid, C. Primary mediastinal lymphoma, D. Non-Hodgkin lymphoma
A: Thymoma
Answer: A: Thymoma 
Explanation: . Thymoma