Shelton measures a temperature of a solution to be 20O degrees C and stirs 5 grams of a substance into the solution. this substance disappears and 10 minutes later the substance of the solution is 80O degrees C. based on his observation, can Shelton conclude a chemical reaction has occurred?

A) yes because the substance dissolved in the solution

B) no because the volume of the solution did not change

C) no because there are no color changing solution

D) yes because heat was produced