Population density is a measurement of population per unit area, or exceptionally unit volume; it is a quantity of type number density. It is frequently applied to living organisms, most of the time to humans. It is a key geographical term. Hope this answered your question
It would be letter A which is energy. The other three are used in weather forecasting due to the fact that the atmosphere is fluid and weather and climate is caused by uneven heat from the star in our solar system which is the Sun to the Earth in which heat transfer occurs
Probably look in the middle of the cloud and then try to figure it out through the density it seems to be. lol
