Athletes training at high altitudes adapt to air with lower oxygen levels than air at sea level. Which cells are most likely to increase in number as a result of this adaptation?

At high altitudes, the air contains less oxygen, so the body adapts by producing more red blood cells. Red blood cells carry oxygen from the lungs to the body's tissues, helping deliver enough oxygen despite the thinner air. Therefore, red blood cells are most likely to increase in number.

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