Which of the following causes stagnant hypoxia?

Stagnant hypoxia occurs when blood flow is insufficient to meet the oxygen demands of the body, leading to decreased oxygen availability in the tissues despite adequate oxygen levels in the blood. This condition can arise due to various factors that affect circulation, one of which is cold temperatures.

Cold exposure can cause peripheral vasoconstriction, the narrowing of blood vessels in the extremities. This response is the body's way of preserving core temperature but can also reduce blood flow to those areas. If the overall circulation is compromised due to chilling effects on the cardiovascular system, it may lead to stagnant hypoxia, as the tissues might not receive enough oxygenated blood to function effectively.

The other options, while related to oxygen availability and physiological stress, do not directly cause stagnant hypoxia in this manner. For instance, carbon monoxide affects hemoglobin's ability to carry oxygen rather than blood flow itself, alcohol impacts overall cognition and motor function, and loss of cabin pressurization leads to hypoxia through reduced atmospheric pressure rather than stagnant blood flow.