The water table is the a. zone of aeration. b. upper boundary of the zone of saturation. c. aquifer. d. lower boundary of the zone of saturation.

The correct answer is B. upper boundary of the zone of saturation.

This means that this is the part where the water pressure head is equal to the atmospheric pressure. The water table changes its size and behavior based on the topography and even based on the seasons with there being different water tables based on whether it's summer or winter.