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': 'Shadow test is used in \nSelect and explain. \nA. Ophthalmoscopy, B. Gonoioscopy, C. Retinoscopy, D. Keratometry', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Shadow test in Retinoscopy : Fundal reflex casting shadow in pupillary area.', 'role': 'assistant'}]