Devin investigated whether salt reduces the boiling point of water. She poured 1 gallon of 18 degrees Celsius (°C) water into a pot and added 2 cups of salt to it. Devin heated it over a fixed flame and measured the temperature when the water reached a rolling boil. She repeated the experiment with 1 gallon of water and 4 cups of salt under identical conditions. Where did Devin make a mistake in her experimental design? She did not boil a pot of water without salt.

She waited until the water reached a rolling boil.

She used different amounts of salt in the two pots.

She did not heat the pots of water at the same time.