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 showing brownish pigmentation and with
normal laboratory findings may be suffering from: 
Select and explain. 
A. Addison's disease, B. Fibrous dysplasia, C. Neuro fibromatosis, D. None of the above
C: Neuro fibromatosis
Answer: C: Neuro fibromatosis 
Explanation: None