To an Observer Traveling Outward from the Earth's Surface into Outer

To an observer traveling outward from the Earth's surface into outer space,the temperature of the atmosphere ________.

A) uniformly decreases because of atmospheric thinning
B) uniformly increases because of increasing proximity to the Sun
C) fluctuates depending on the atmospheric layer
D) remains relatively constant until the very edge of the atmosphere,where the observer would experience the very cold vacuum that is interplanetary space