Where is the water table located?
a. 10 ft below the surface
b. below the saturated zone
c. at the top of the saturated zone
d. all of the above

We have to choose the correct answer about the location of the water table. The water table is an upper level of an underground surface in which the soil or rocks are permenently satureted with water. So it is over the saturated zone. It is where the rock or soil begin to be filled ( or "saturated" ) with water. The water table is C. at the top of the saturated zone.

The independent variable would be the fertilizer as it is what the dependent variable (the growth of grass) depends on.