The right option is; the water table
The upper limit of the zone of saturation is called the water table.
Water table is the top level of an underground surface where the rocks or pores of the ground are indelibly saturated with water. The water table removes the zone of aeration that is situated on top of it from the groundwater zone that is situated beneath it. Certain conditions such as amount of precipitation used by plants, climatic differences, and withdrawal of large amounts of water from wells, affect the water table and make it to fluctuate both with the seasons and from year to year.
