Concept:Water is the only factor among the options that acts as both a physical and a chemical agent of rock weathering.
Explanation:Water causes physical weathering through freeze-thaw action, when it enters cracks in rocks, freezes, expands, and breaks the rocks apart.
Water also causes chemical weathering by reacting with minerals in rocks through processes like hydration, hydrolysis, and dissolution.
Temperature mainly causes physical weathering through repeated heating and cooling.
Animals bring about biological weathering rather than chemical weathering.
Oxygen primarily causes chemical weathering through oxidation.
Therefore, water is the factor that performs both physical and chemical weathering.
Answer:C. water