A 29-year-old woman presents with fluctuating ptosis and diplopia worsening toward evening. She reports fatigue when chewing tough foods, with strength improving after brief rest. Vital signs are stable (BP 118/76, HR 72, RR 14, Temp 37°C, SpO2 98%). Serum anti-acetylcholine receptor antibodies are positive. Neuroimaging shows no intracranial masses. She denies recent infections or medication changes. Which of the following is the most likely diagnosis?

1. A)Myasthenia gravisGABARITO
2. B)Guillain-Barre syndrome
3. C)Amyotrophic lateral sclerosis
4. D)Lambert-Eaton myasthenic syndrome
5. E)Botulism