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 50 year old man presented with orbital mass. Systemic examination revealed anaemia and investigations revealed hypergammaglobulinemia. The patient should be investigated to rule out: - 
Select and explain. 
A. Squamous cell carcinoma, B. Optic nerve glioma, C. Multiple myeloma, D. Malignant melanoma
C: Multiple myeloma
Answer: C: Multiple myeloma 
Explanation: None