Final answer:
Adapting to higher altitudes involves acclimatization, where the body compensates for the lower oxygen levels by producing more erythrocytes, thus increasing blood oxygen levels over time.
Step-by-step explanation:
How a person adapts to altitude over a period of time involves several physiological changes, primarily aimed at compensating for the lower oxygen levels present at high altitudes. This process is known as acclimatization.
With an increase in altitude, the atmospheric pressure and oxygen concentration decreases, leading to a condition known as hypoxia, where there is an inadequate supply of oxygen to the body. The body responds by increasing the production of the hormone erythropoietin (EPO), which stimulates the production of more erythrocytes (red blood cells). These additional red blood cells increase the hemoglobin count in the blood, allowing for more efficient transport of the reduced oxygen available. Over time, typically around 10 days, this process facilitates improved oxygen delivery to tissues and helps the body adjust to the new environmental conditions, thus avoiding acute mountain sickness (AMS).
Therefore, the correct answer to how a person adapts to altitude over a period of time would be c) Increased blood oxygen levels, as the increased red blood cell count allows for higher oxygen transport capacity despite lower hemoglobin oxygen saturation at high altitudes.