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: Surgery
Prognosis of malignant melanoma depends on ? 
Select and explain. 
A. Grade of tumor, B. Spread of tumor, C. Depth of invasion, D. Metastasis
C: Depth of invasion
Answer: C: Depth of invasion 
Explanation: Ans. is 'c' i.e., Depth of invasion