In Convectional Current Theory surface spreading is linked with which situation?

Correct answer: Upwelling of mantle material

The direct answer is A: upwelling of mantle material. In convectional current theory, hot mantle material becomes less dense and rises. When it reaches a higher level beneath the surface, it can move sideways in opposite directions. This outward movement produces spreading at the surface, especially near a mid-ocean ridge. As material rises and spreads, new ocean-floor material may form. Option A is correct because rising mantle material supplies the movement that leads to surface spreading. Option B is wrong because completely still material cannot create a current or spreading. Option C is unrelated: frozen river water is a surface-water event, not mantle movement. Option D is also unrelated because stopping wind does not explain tectonic spreading. Remember the chain: heat causes rising, rising causes sideways movement, and sideways movement causes spreading.