Task: Question Answering
Input (English): A substance with a mass of 10 g is heated to produce two new substances. The mass of the first new substance is 9.3 g and the mass of the second new substance is 0.7 g. Which of the following is best demonstrated by this example?  
 (A) heat transfer (B) physical change (C) law of conservation of mass (D) law of conservation of energy
Output (English): C