Answer:
Option C, As elevation increases, air pressure decreases, molecules spread out, and air temperature cools.
Explanation:
As we move towards the sky the number of air particles reduces and hence its density also reduces. Due to lesser number of particles the pressure exerted by air also reduces at high elevations.
As per the gas law

Where P is the pressure, V is the volume, n is the number of mole, R is the gas constant and T is the temperature.
Gas law states that if volume is constant, the relation between temperature and pressure is proportional.
Thus, if pressure is reducing the temperature will also reduce.
Hence, option C is correct