5. a pacific mp air mass moving inland (eastward) and across the united states often produces conditions along the western slopes of mountain ranges it crosses.

a hot and humid
b dry and hot
c wet and unstable
d dry and stable

The correct answer is C. Wet and unestable

Explanation:

The mP Air mass type is characterized for being mild and humid and it is commonly formed to the North Pacific, in United States, because its high latitudes. When it moves inland (Eastward) cold air meets warm air provoking  unestable conditions in the atmosphere boosting the formation of clouds, and subsequently, precipitation. Then, when decending over the western slopes of mountain, it is moist and can produce rain and snow.