Answer:
Volcanoes form in the central rift valley of a divergent boundary when two tectonic plates move away from each other. This is because the plates create a gap in the Earth's crust between them, which allows molten rock from the mantle below to rise up and form a volcano. This molten rock is called magma, and when it rises to the surface it is called lava. As the tectonic plates move away from each other, the gap created by them is constantly widened, allowing more magma to escape and form a volcano.