Please choose the correct answer to the question: Two identical lamps contain the same amount of different types of oil. They are allowed to burn until all the oil has been burned. Which measurement will best provide the total difference in chemical energy between the two oils?

Answer1: final weight of lamp Answer2: original volume of oil Answer3: time it took for lamps to use oil Answer4: height of flame produced by lamp

Answer format: answer1/answer2/answer3/answer4