4. what is the mean amount of rainfall?

The middle value of aggregate sum of precipitation recorded during a schedule month or year is called as mean amount of rainfall. Both mean and middle precipitation are incorporated into these insights, despite the fact that from the meteorological perspective, the middle is generally the favored proportion of 'normal' or 'ordinary' precipitation.

This is a direct result of the high inconstancy of day by day precipitation - one outrageous precipitation occasion, (for example, a gradually moving, serious rainstorm) will have less effect on the middle than it will have on the math mean.

i believe that the answer is c.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.