Task: Question Answering
Input (English): Background Paragraph: The epidermis also contains melanocytes , which are cells that produce melanin. Melanin is the brownish pigment that gives skin much of its color. Everyone has about the same number of melanocytes, but the melanocytes of people with darker skin produce more melanin. The amount of melanin produced is determined by heredity and exposure to UV light, which increases melanin output. Exposure to UV light also stimulates the skin to produce vitamin D . Because melanin blocks UV light from penetrating the skin, people with darker skin may be at greater risk of vitamin D deficiency. 
Story: John is learning more about different cultures and people around the world. He noticed that people have different skin colors. To learn more about the science behind skin colors he categorized the skin colors into two broad groups, case D and case L. Case D is represented by darker skin and case L is represented by lighter skin. 
Question: People in which case would have greater risk of vitamin D deficiency, case D or case L?
Output (English): case D.