Explain the rock cycle and how metamorphic rocks can become igneous or sedimentary rocks.

• A. Rocks never melt; metamorphism never happens.
• B. Rocks weather and erode to form sediments; sediments lithify into sedimentary rocks; burial + heat/pressure metamorphose rocks into metamorphic; melting produces magma that can crystallize into igneous rocks; deep recycling closes the cycle.
• C. Igneous rocks always turn into sedimentary; sedimentary never metamorphose.
• D. Only sedimentary rocks can become metamorphic.

Answer: (B)

Rocks change form through a set of connected processes that make up the rock cycle. Weathering and erosion break rocks down into sediments, which can be deposited and lithified into sedimentary rocks. Heat and pressure from burial or tectonic forces transform rocks into metamorphic rocks with new textures and minerals. If rocks melt, they become magma that can rise, cool, and crystallize into igneous rocks, restarting that branch of the cycle. From any rock type, weathering, erosion, deposition, and lithification can lead to sedimentary rocks, while metamorphism or melting can convert rocks into other forms as conditions change.

The best choice captures this flow: metamorphic rocks form from existing rocks under heat and pressure; they can melt to magma and crystallize into igneous rocks, or be weathered and lithified into sedimentary rocks, completing the cycle with deep recycling. Rocks never melting and metamorphism never occurring, as another option suggests, is inaccurate. Likewise, saying igneous rocks always become sedimentary ignores melting and re-crystallization pathways, and claiming only sedimentary rocks can become metamorphic overlooks that any rock type can undergo metamorphism.