Low concentration of oxygen in the blood and tissues of people living at high altitude is due to:

Low atmospheric pressure.

The correct answer is Option (2) → Low atmospheric pressure

The low concentration of oxygen in the blood and tissues of people living at high altitudes is primarily due to: Low Atmospheric Pressure.

At high altitudes, the atmospheric pressure is significantly lower than it is at sea level. This decrease in pressure results in a lower partial pressure of oxygen in the air. Since the amount of oxygen available for breathing is directly related to the partial pressure of oxygen, individuals at high altitudes receive less oxygen with each breath.

Explanation of the Options:

1. Low Temperature:

While temperature can affect the solubility of gases, it is not the primary factor causing low oxygen levels at high altitudes. Low temperatures are more relevant in certain contexts (like affecting metabolism) but do not significantly contribute to the low oxygen concentration in blood at high elevations.

2. Low Atmospheric Pressure:

This is the correct answer. At high altitudes, the reduced pressure leads to a lower density of air and subsequently a lower availability of oxygen. This causes hypoxia (a deficiency in the amount of oxygen reaching the tissues).

3. High Atmospheric Pressure:

This option is incorrect, as high atmospheric pressure is generally associated with increased availability of oxygen, not decreased.

4. Both Low Temperature and High Atmospheric Pressure:

This is also incorrect, as high atmospheric pressure is not a factor at high altitudes. The primary reason for low oxygen levels is the low atmospheric pressure.

Conclusion

The correct answer is: Low atmospheric pressure.