Kevin's science class did an experiment using baking soda, vinegar, a red balloon, and a flask. First, they filled the flask with vinegar and poured baking soda into the deflated balloon. Then, they placed the balloon over the mouth of the flask, being careful not to let the baking soda fall into the vinegar. They observed that the balloon was still deflated. Next, the students held the balloon up and allowed the baking soda to fall into the flask and mix with the vinegar. The mixture began to bubble, and the balloon began to inflate. Kevin thinks that a new substance must have been formed when the baking soda mixed with the vinegar. To help support this idea, Kevin makes several observations about the flask, the balloon, and the substance inside the flask after the baking soda and vinegar were mixed. Which of these observations provides the best evidence that a new substance formed? A. The liquid in the flask is clear. B. The balloon is inflated. C. The balloon is red. D. There is liquid in the flask.