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
Spastic paraplegia can be caused by the following except - 
Select and explain. 
A. Motor neuron disease, B. Chronic lead poisoning, C. Vitamin B12deficiency, D. Cervical spondylosis
B: Chronic lead poisoning
Answer: B: Chronic lead poisoning 
Explanation: None