In which of the following best explains the decrease in temperature with height within the lower layers of the atmosphere?

• A.The air receives its heat directly from the sun's rays
• B.The earth is the main source of the heat given up to the air
• C.An increases in height is associated with increase in rainfall
• D.There are always water particies in the air at high altitudes
• E.There is little mixing of air at higher altitudes