Pigments in the skin act like a filter that can prevent the skin from making vitamin D. As a result, people with darker skin need more time in the sun than people with lighter skin to make the same amount of vitamin D.

Two friends are headed to the beach, Mike and John. Mike is white, and John is black. Both want to make the same amount of vitamin D through sun exposure. The person who will take longer to make the amount of vitamin D is Mike or John? 

