A rock in a harsh desert is slowly breaking down over time. Temperatures in the desert rise quickly during the day and fall quickly at night. These temperature changes cause stress in the rock, and as a result, it is slowly breaking apart. Which of the following processes is happening to this rock?

Rapid heating during the day and cooling at night make the rock expand and contract. Repeated temperature changes create stress that breaks the rock into smaller pieces without changing its chemical composition. This is physical weathering, so the best answer is B, physical weathering.

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