Please choose the correct answer to the question: An experiment is being conducted to determine the air quality inside a building. In order to come to a conclusion, scientists must gather data. Which of the following would be an excellent source of data from which to draw a conclusion?

Answer1: naked-eye viewing Answer2: calculations of air mass Answer3: demonstrations of air pressure Answer4: measurement of airborne particulates

Answer format: answer1/answer2/answer3/answer4