Asharp, irregularly shaped rock falls into a river. over time, the edges of the rock become smooth and rounded by rubbing against other rocks. this is an example of
a : chemical weathering
b : biological weathering
c : physical weathering

The answer is C.
Chemical weathering is when something changes other than the way something looks. Biological weathering is not even an option. So that leaves physical weathering. Physical weathering is when something changes on the outside physically that is caused by weather.

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