Final answer:
At high altitudes, the amount of air molecules decreases, the air temperature generally decreases, and the air pressure decreases as well. Accordingly.
The correct option for what happens at high altitudes is option a). (1) Decreases, (2) Decreases, (3) Decreases
Step-by-step explanation:
At high altitudes, the following changes occur to the atmosphere:
The amount of air molecules decreases due to the decrease in air density. The number of molecules in a given volume of air becomes lesser as the altitude increases.
The temperature of air generally decreases with altitude, although this can vary under some atmospheric conditions and at different layers of the atmosphere.
Air pressure also decreases at higher altitudes. As you climb higher, the weight of the overlying atmosphere reduces, which results in a lower atmospheric pressure.