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

Answer

C