Define "artesian well."

An artesian well is characterized by its ability to bring water to the surface without the need for mechanical pumping. This phenomenon occurs when a well is drilled into a confined aquifer, where water is trapped between layers of impermeable rock or clay. The natural pressure within the aquifer forces the water to rise above the ground level, often resulting in the water bubbling up spontaneously and flowing freely from the well. This characteristic distinguishes artesian wells from other types of wells, which typically require pumps to draw water from the ground.

In contrast to the other options, a well that requires mechanical pumping denotes a non-artesian well where external energy is necessary to extract water. A shallow groundwater extraction point does not specify the pressure dynamics involved, and a sealed well refers to a structure designed to prevent surface contamination but does not accurately capture the pressure-driven flow characteristic of an artesian system. Thus, the defining feature of an artesian well is the natural pressure of the confined groundwater that causes it to rise to the surface without additional pumping.