Biologists Believe That the Change in the HIF2a Gene Frequency

Multiple Choice

Biologists believe that the change in the HIF2a gene frequency among Tibetans may be the fastest case of human evolution yet discovered. What is the selection pressure affecting this gene?

A) The low atmospheric pressures experienced on the high-altitude Tibetan Plateau.
B) The low atmospheric concentration of O₂ that occurs at high altitude.
C) The increased solar, particularly UV, radiation experienced at high altitude.
D) A diet consisting primarily of high-altitude-tolerant crops.