This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
What is the basic minimum illumination required for satisfactory vision?- 
Select and explain. 
A. 10-15 foot candles, B. 15-20 foot candles, C. 20-25 foot candles, D. 25-30 foot candles
B: 15-20 foot candles
Answer: B: 15-20 foot candles 
Explanation: (PARK TB 23rd edtn pg 739) The lighting should be sufficient to enable eye to discern the details of an object as well as the surroundings without eye strain. An illumination of 15 to 20 candles is accepted as the basic minimum for satisfactory vision.