A 34-year-old man presents with progressive bilateral leg weakness and paresthesias beginning one week after acute diarrheal illness. Vital signs: BP 118/76, HR 92, RR 18, Temp 37.2°C, SpO2 98% on room air. Physical examination reveals areflexia in both lower extremities; upper extremity reflexes remain intact. Serum electrolytes and glucose are normal. CSF protein is markedly elevated at 89 mg/dL with normal cell count. Which of the following is the most likely diagnosis?

1. A)Myasthenia gravis
2. B)Multiple sclerosis
3. C)Amyotrophic lateral sclerosis
4. D)Poliomyelitis
5. E)Guillain-Barre syndromeGABARITO