Why does cooler material sink in a convection current?

Correct answer: Because its density increases as it cools

As material cools in a convection current, its volume generally decreases while its mass remains nearly the same. Its density therefore increases. The cooler, denser material sinks below the surrounding warmer, less-dense material. Hence, option A is correct. Option B is the closest distractor, but cooling generally decreases rather than increases volume. Exam tip: in convection, warm low-density material rises, while cool high-density material sinks.