How do plants most commonly break large rocks into smaller pieces

Plants most commonly break large rock into smaller pieces by having the plant root grow into cracks in rocks. The plant root from below the surface grows and that's how they break rocks into pieces.

There are several ways for plants to break large rocks into smaller pieces, such as :

- Plant Grows roots into the rocks and crack it from the inside
- they can leave insulate surrounding rocks from extreme temperatures
- Plants' seeds can contain acidic substance that will slowly deteriorate the rocks when it falls 

Combustion is the act or process of burning. therefore, i believe the answer is  a: burning wood. 

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