A student performs an experiment and the results are shown below. Before: Iron filings are brown, small, and magnetic; copper sulfate crystals are blue, brittle, and not magnetic. After: The copper formed was reddish, solid, and not magnetic; iron sulfide solution was colorless and not magnetic. Which statement supports that a chemical reaction took place? A. The original substances were present after. B. A physical change in the iron occurred. C. Changes in color occurred. O D. A new substance was formed.​