Why is it harder to breathe when climbing up a high mountain?(1 point)

Responses

The air pressure increases.
The air pressure increases.
The air is thinner.
The air is thinner.
The air compresses the lungs.
The air compresses the lungs.
The air has more moisture.

The air is thinner.

Well I guess "thinner" is indeed the best of the choices but I would have said the pressure went down decreasing the density of the air.

You are correct. I apologize for the confusion. The air pressure decreases at high altitudes, resulting in a decrease in the density of the air. This decrease in air density makes it harder to breathe when climbing up a high mountain.