What are faults?

• A. Harbours of tectonic plates
• B. Plate boundary zones where earthquakes do not occur
• C. Cracks in the earth's surface along which earthquakes occur
• D. Regions where rivers meet the sea

Answer: (C)

Faults are cracks in the Earth's crust where rocks on either side have moved relative to each other. Tectonic forces shear and compress the rocks until they fracture, and the sudden slip along the fault releases energy as earthquakes. So, faults are the places where movement on fractures enables seismic activity. The other options describe features that aren’t about rock fractures or seismic slip—one is a port for tectonic plates, another says earthquakes don’t occur at some plate boundary zones (which is incorrect, since many earthquakes align with faults at plate boundaries), and another is a river delta rather than a structural feature in the crust.