A Mountain Top Is an Especially Good Site for Infrared

Multiple Choice

A mountain top is an especially good site for infrared telescopes since:

A) there you are closer to celestial objects.
B) you are above most of the carbon dioxide and water vapor in the atmosphere.
C) the cold weather helps the sensitivity of infrared detectors.
D) less air above means better seeing in many cases.
E) All of the above are factors.