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
Unit of light emitted from a surface is: 
Select and explain. 
A. Lambe, B. Candella, C. Lux, D. Lumen
D: Lumen
Answer: D: Lumen 
Explanation: Ans. LumeLumen