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 of more than 70 years, presented with generalized lymphadenopathy, WBC count was 20,000/mm3 and blood film showed >70% mature looking lymphocytes. Next investigation that should be done - 
Select and explain. 
A. LN Biopsy, B. Peripheral Immunohistophenotyping, C. Bone marrow aspiration, D. Peripheral blood cytogenetics
B: Peripheral Immunohistophenotyping
Answer: B: Peripheral Immunohistophenotyping 
Explanation: . Peripheral Immunohistophenotyping