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': "Sling surgery should be avoided in cases of ptosis with: \nSelect and explain. \nA. Very poor levator action, B. Poor Bell's phenomenon, C. Weak Muller's muscle, D. Multiple failed surgeries", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. Poor Bell's phenomenon", 'role': 'assistant'}]