Which of these things does not show that a reaction has occurred?

A The mixture gets hotter

B The substance changes from a liquid to a solid.

C The mixture changes colour.

D Bubbles of gas form in the mixture.

If my hypothesis is correct, the answer should be B. All answers, A, C, and D are chemical reactions. They are all reactions, but B does not fit the category, so they only answer could really be B. (I debated between both A and B because those are the only answers that can be correct)

I believe it may be C. Because, the color changing has nothing to do with the reaction you get.