Question

as streams flow through stone mountain, layers of sand build up. over time, the sand particles form a sedimentary rock called sandstone.
what causes sandstone to change into metamorphic rock at stone mountain?
sandstone is reshaped by erosion from a stream.
sandstone builds up layers of sand at the mountain.
sandstone experiences intense heat and pressure.
sandstone has more sand particles compacted on top of it.

Explanation:

Metamorphic rocks form from existing rocks (like sandstone) under intense heat and pressure. Erosion reshapes rocks but doesn't turn them metamorphic. Building - up layers of sand is sedimentation, not metamorphosis. Just adding more sand particles on top is compaction in sedimentary rock formation, not enough for metamorphosis.

Answer:

Sandstone experiences intense heat and pressure.