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': 'Muscae volitantes are seen in \nSelect and explain. \nA. Vitreous detachment, B. Vitreous hemorrhage, C. Eale’s disease, D. Remains of primitive hyaloid vasculature', 'role': 'user'}, {'content': 'Answer: D \nExplanation: These are physiological opacities and represent the residues of primitive hyaloid vasculature.\nPatient perceives them as fine dots and filaments, which often drift in and out of the visual field, against a bright background (e.g., clear blue sky).', 'role': 'assistant'}]