Ravi, who lived at sea level, had around 5 million RBC per cubic millimeter of his blood. Later when he lived at an altitude of 18,000 ft, showed around 8 million RBC per cubic millimeter of blood. This is an adaptation because

Options

A. At high altitude he ate more nutritive food
B. He had pollution free air to balance breathe
C. At high altitude `O_(2)` level is less hence more RBCs were required to absorb enough oxygen
D. At high altitude there is more UV readiation which enhances RBCs production

Answer

c