Final answer:
An air mass has similar temperature and moisture properties throughout. Uniformity of such properties defines an air mass, which can affect precipitation patterns when interacting with geographical features like mountain ranges.
Step-by-step explanation:
The correct statement regarding the properties of an air mass is that an air mass has similar temperature and moisture properties throughout it. Air masses are large bodies of air that cover significant portions of the Earth, and they tend to have uniform temperatures and moisture levels within them. Air masses can be influenced by the surface over which they form; for instance, those forming over oceans are generally more moist, while those forming over land tend to be drier. As an air mass moves over different terrains and altitudes, such as mountain ranges, precipitation patterns can change due to the orographic effect. The air cools as it rises over a mountain, leading to rain on the windward side and creating a rain shadow on the leeward side with drier conditions. The global pattern of precipitation and distribution of dry and humid areas is partly determined by these air mass characteristics and their movements.