Final answer:
The answer is option (B) - Change in state. While the other options listed - change in color, change in temperature, and formation of a precipitate - are all indicators of a chemical reaction, a change in state refers to a physical change rather than a chemical one.
Step-by-step explanation:
The answer is option (B) - Change in state. While the other options listed - change in color, change in temperature, and formation of a precipitate - are all indicators of a chemical reaction, a change in state refers to a physical change rather than a chemical one. A chemical reaction involves the transformation of substances into new substances with different properties. It may result in changes in color, temperature, or the formation of a precipitate.