In the Section "Investigating Life: Vitamins and the Evolution of Human

In the section "Investigating Life: Vitamins and the Evolution of Human Skin Pigmentation",how did the scientists test their hypothesis?

A) The scientists mapped measurements of annual exposure to UV radiation on land and three categories of UV reflectance of the skin of indigenous people.
B) The scientists sampled vitamin D and folic acid levels in indigenous people around the world and compared it to three categories of UV reflectance of the skin.
C) The scientists mapped measurements of annual exposure to vitamin D and compared it to three categories of melanin production.
D) The scientists mapped measurements of annual exposure to folic acid and compared it to three categories of melanin production.