Answer: The correct answer is option A, the best source region for an air mass are generally flat areas of uniform composition with light surface winds.
Explanation:
Source Regions may be defined as parts of the Earth's surface where the air can remain in one position over a long period of time (stagnate) and slowly begin to gain properties of the underlying surface. It is also important to note that the main source regions include:
1) the high pressure belts which is located in the subtropics (which give rise to tropical air masses)
2) around the earth poles (which is the source for polar air masses).
However, the best source region are generally flat areas of orderly(uniform) composition with light(not too heavy) surface winds.
