What natural element is vital to the body's ability to make vitamin D?
a. iron
b. sunshine
c. chlorinated water
d. selenium
Question 2
Today, food-foraging societies:
a. are found only in the world's most marginal areas.
b. make up the majority of the world's population.
c. have not existed for 1,000 years.
d. have their pick of the best environments.
e. represent a primitive, undeveloped way of life.
