This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Ophthalmology
[{'content': 'Universal marker of limbal stem cells- \nSelect and explain. \nA. Elastin, B. Keratin, C. ABCG2, D. Collagen', 'role': 'user'}, {'content': 'Answer: C \nExplanation: *Universal marker of limbal stem cells is ABCG2 Ref:Human Adult Stem Cells edited by John Masters, Bernhard Palsson p.117', 'role': 'assistant'}]