Which option correctly states the river process of lake formation?

Correct answer: Cutting off of a meander and formation of isolated water

The direct answer is A: a meander can be cut off, leaving an isolated water body. In a winding river on a plain, erosion is stronger on the outer bank while deposition occurs on the inner bank. Step by step: the bend becomes narrower at its neck; during high flow or flooding, the river cuts through the narrow neck; the main channel becomes straighter; the abandoned curved part remains separated from the river and forms an oxbow lake, usually crescent-shaped. Option A is correct because it describes this river process. Option B is wrong because an ordinary rock does not change into a volcano through lake-forming river action. Option C is wrong because sea waves do not become glaciers; glaciers form from accumulated snow and ice. Option D is wrong because wind does not transform into a river. Remember: cut-off meander equals oxbow lake.