If vinegar is added to baking soda, the reaction Cu (s) + 2Ag(NO3) (aq) à 2Ag (s) + Cu(NO3)2 (aq) occurs. What evidence would indicate that the reaction is occurring?
 a. a precipitate is formed
 b. light and heat are given off
 c. a new odor is given off
 d. the solution bubbles