Question

Why do mountaineers become breathless as they reach high altitudes?

A.
because water vapor concentration decreases as altitude increases
B.
because air pressure increases as altitude increases
C.
because oxygen concentration decreases as altitude increases
D.
because air temperature increases as altitude increases

Answer 1

C. Oxygen concentration decreases as altitude increases

Step-by-step explanation:

Higher altitudes have lower levels of oxygen and decreased air pressure.