Which desalination method uses membranes under pressure to remove salt from seawater?

• A. Distillation
• B. Desalination
• C. Reverse Osmosis
• D. Aquifers

Answer: (C)

Desalination via pressure-driven membranes is what this item is about. In this approach, seawater is forced through semi-permeable membranes under high hydraulic pressure. Water passes through while most dissolved salts are retained, delivering freshwater on the other side. The applied pressure must overcome the natural osmotic pressure to drive water across the membranes, which is why this method is called reverse osmosis. Distillation relies on heating and phase change to separate water from salts, not membranes under pressure. Aquifers are underground water sources, not a desalination method. Desalination is the broad field, but it does not specify the mechanism of salt removal like a pressure-driven membrane does.