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': 'Confirmatory investigation in retinitis pigmentosa is \nSelect and explain. \nA. Optical coherence tomography, B. Pachymetry, C. Visual Acuity testing, D. Electroretinogram', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer- D. ElectroretinogramAn accurate diagnosis of retinitis pigmentosa relies on the documentation of the progressive loss photoreceptor cell function, confirmed by a combination of visual field and visual acuity tests, fundus and optical coherence imagery, and electroretinography.', 'role': 'assistant'}]