Lactose Intolerance in Humans Is the Inability to Digest a Specific

Lactose intolerance in humans is the inability to digest a specific sugar found in milk and some milk-derived dairy products. This milk sugar is called lactose, and it is broken down into two simple sugars, glucose and galactose, by the enzyme lactase. Symptoms of this disease, which occur after a person consumes significant amounts of lactose, include abdominal bloating and cramps as well as diarrhea and nausea. Many mammalian species become lactose intolerant shortly after weaning. At this time, the gene that produces lactase becomes inactive so that the enzyme is no longer produced. However, some human populations (approximately 25 percent of all adults) have developed lactase persistence, in which lactase is continually produced throughout adulthood. Which of the following human populations likely evolved lactase persistence?

A) populations living on islands
B) populations in which milk is a component of the diet throughout an individual's life
C) populations in which milk-derived products are essential for young individuals
D) Lactase persistence will evolve in any population that has a strong need for digesting milk.