This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
Minimum amount of GI bleed to cause malena is 
Select and explain. 
A. 10 ml, B. 40 ml, C. 60 ml, D. 115 ml
C: 60 ml
Answer: C: 60 ml 
Explanation: Melaena refers to the passage of typical black, tarry coloured foul smelling stool. It signifies upper GI bleed. At least 50-60 ml bleeding should be there to cause melaena. Reference : page 834 SRB's manual of surgery 5th edition