Andeans (people who live on the Andean mountains of South America) have more oxygen-carrying ___ in their blood.red blood cellsplateletswhite blood cellswater

The correct answer is red blood cells.

Explanation

The Andean people, who inhabit high-altitude regions, have adapted to the low oxygen levels found at high elevations. One significant adaptation is an increase in the number of red blood cells (RBCs) in their blood. Red blood cells are crucial for transporting oxygen from the lungs to the rest of the body.

In high-altitude environments, less oxygen is available to breathe, so having a higher concentration of red blood cells allows the Andeans to more efficiently transport the limited oxygen they receive through respiration. This physiological change is a form of acclimatization that occurs not just in Andeans but also in other populations living at high altitudes, such as Tibetans and Ethiopians.

In contrast, platelets, white blood cells, and water play different roles in the body, but they do not primarily facilitate oxygen transport. Red blood cells are specifically designed for this function, making them the correct choice in the context of adaptations to high altitude living.