This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Free Radical Injury, Subject name: Pathology
Most reactive free radical is: 
Select and explain. 
A. Superoxide, B. Hydroxyl, C. Peroxide, D. Carboxyl
B: Hydroxyl
Answer: B: Hydroxyl 
Explanation: Hydroxyl radical is the most reactive free radical.