Question

how does sediment form?
molten rock cools below earths surface.
loose material is compacted by pressure.
weathering breaks down rock and other materials.
chemical changes cause sediment to cement together.

Explanation:

Sediment forms when weathering (physical, chemical, or biological processes) breaks down rocks and other materials into smaller particles. Molten rock cooling forms igneous rocks. Loose material compacted by pressure is part of sedimentary rock formation (lithification - compaction stage, but sediment itself is the loose particles first). Chemical changes causing sediment to cement together is also part of lithification (cementation), not the formation of sediment.

Answer:

Weathering breaks down rock and other materials.