This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
H-reflex is done in 
Select and explain. 
A. L 2 radiculopathy, B. L 3 radiculopaty, C. L 4 radiculopaty, D. S 1 radiculopty
D: S 1 radiculopty
Answer: D: S 1 radiculopty 
Explanation: The H-reflex is a reflectory reaction of muscles after electrical stimulation of sensory fibers in their innervating nerves. The H-reflex test is performed using an electric stimulator, which gives usually a square-wave current of sho duration and small amplitude, and an EMG set, to record the muscle response. Ref Harrison20th edition pg 2567