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': 'Asthenopic symptoms are most marked with: \nSelect and explain. \nA. Cyclophoria, B. Hyperphoria, C. Esophoria, D. Exophoria', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Cyclophoria', 'role': 'assistant'}]