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: Medicine
Most important diagnostic sign of upper motor neuron
syndrome: 
Select and explain. 
A. Exaggerated tendon reflexes, B. Babinski's sign -ve, C. Absent superficial reflexes, D. Lead pipe rigidity
A: Exaggerated tendon reflexes
Answer: A: Exaggerated tendon reflexes 
Explanation: None