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: Physiology
The most common problem with blood transfusion is: 
Select and explain. 
A. Hemolytic reaction, B. Remission of disease, C. Hypokalemia, D. Metabolic acidosis
A: Hemolytic reaction
Answer: A: Hemolytic reaction 
Explanation: None