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: Medicine
A patient presents with macroglossia and loss of tongue papilla. His Hb is 11.5 and MCV is 100. What should be the next step in investigating this patient? 
Select and explain. 
A. B12 estimation, B. Brush biopsy of the lesion, C. Fluconazole treatment, D. Incision biopsy
A: B12 estimation
Answer: A: B12 estimation 
Explanation: None