An aquifer where the water is under pressure is called what?

• A. Arable farming
• B. Artesian aquifer
• C. Asthenosphere
• D. Benioff zone

Answer: (B)

This question tests understanding of groundwater pressure and how certain aquifers behave. An aquifer that is trapped between impermeable layers becomes confined, and recharge at a higher elevation creates hydraulic pressure. When the water-bearing rock is under pressure like this, a well drilled into it can bring water to the surface without pumping—the water rises because of that natural pressure. That situation is known as an artesian aquifer.

Arable farming, asthenosphere, and the Benioff zone are not related to groundwater pressure or the way certain aquifers push water to the surface. Arable farming is about cropping, the asthenosphere is a layer of the Earth's mantle, and the Benioff zone is a submarine earthquake region.