A ____________is formed when ground water enters cracks in limestone

• A. Cavern
• B. Canyon
• C. Grotto
• D. Sinkhole

Answer: (A)

Groundwater dissolving limestone creates underground cavities called caverns. When acidic water from rain seeps into cracks, it slowly dissolves the calcium carbonate in the rock, widening those cracks into larger voids over a long time. These interconnected voids become caverns, large empty spaces beneath the surface. A grotto is a smaller, often decorative cave or water-filled recess, not the typical large underground chamber formed by dissolution. A sinkhole is a surface depression that forms when a cavity above or below the ground collapses, and a canyon is carved by surface water eroding rock. So the feature formed by groundwater entering limestone cracks is a cavern.