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
The most definite feature of a malignant tumour is: 
Select and explain. 
A. Haemorrhage, B. Increased mitoses, C. Metastasis, D. Necrosis
C: Metastasis
Answer: C: Metastasis 
Explanation: None