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: Ophthalmology
[{'content': 'Shanti, aged 27 yrs presented with complaints of difficulty in reading near print. There is ptosis and diplopia in all directions. She is having- \nSelect and explain. \nA. III CN palsy, B. Myasthenia gravis, C. Presbyopia, D. VI CN palsy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Amongst the given options ptosis can be caused by 3rd nerve palsy and myasthenia gravis. However, in 3rd nerve palsy diplopia will not occur on Down & out gaze (due to sparing of SO and LR) while in myasthenia gravis, diplopia will occur in all directions.', 'role': 'assistant'}]