photographs of reactants and products listing of masses of reactants and products listing of time from start to finish of reaction photograph of a flame produced when the chemicals reacted
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A student concludes that a chemical reaction performed in a classroom investigation was exothermic. To communicate the validity of this conclusion, which would make the best visual evidence in a presentation?
Possibilities:
- photographs of reactants and products
- listing of masses of reactants and products
- listing of time from start to finish of reaction
- photograph of a flame produced when the chemicals reacted

photograph of a flame produced when the chemicals reacted