This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fluid, Electrolyte and Nutrition, Subject name: Surgery
Massive blood transfusion is defined as: 
Select and explain. 
A. Whole blood volume in 24 hours, B. Half blood volume in 24 hours, C. 40% blood volume in 24 hours, D. 60% blood volume in 24 hours
A: Whole blood volume in 24 hours
Answer: A: Whole blood volume in 24 hours 
Explanation: Massive transfusion is defined, in adults, as replacement of whole blood volume in 24 hours or >50% of blood volume in 4 hours.