Mountains have an unmatched power to drive human evolution. Starting tens of thousands of years ago, people moved to high altitudes, and there they experienced adaptation that reworked their biology. In Tibet, for example, people have broader arteries and capillaries. In the Andes, they can dissolve more oxygen into their blood. These different traits of people who live in high altitudes illustrate a inclusive fitness because the variation in the number and types of molecules in their blood increases their survival
b. inclusive fitness because the variation in traits is increased by the altruistic behaviors of the Tibetans
c. relative fitness because the variation in the number and types of molecules in their blood is passed on to the next generation
d. relative fitness because the variation in traits is increased by high birth rate and low death rate