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: Biochemistry
Most powerful oxygen free radical is: 
Select and explain. 
A. Hydroxyradical, B. Hydrogen peroxide, C. Superoxide radical, D. Both 1 & 2
A: Hydroxyradical
Answer: A: Hydroxyradical 
Explanation: Most powerful oxygen free radical is Hydroxyradical:

Least powerful Reactive Oxygen species is Hydrogen peroxide.
Precursor of all reactive Oxygen species is Superoxide radical.
H2O2 is not a free radical but a ROS.

Reference- Review of biochemistry by Rebecca James Perumcheril Pg-411