Question

how can we test the hypothesis that bottled water has fewer chemicals than tap water?
multiple choice
measuring the different levels of chemicals in samples of both bottled and tap water
through questionnaires asking a random group of people if they notice differences between bottled and tap water
by observing the two different types of water
comparing sales data from bottled and tap water because people will use more of the water with less chemicals

Explanation:

To test the hypothesis about chemical levels in bottled and tap water, direct measurement of chemicals in samples is the most scientific and relevant method. Questionnaires rely on perception (not actual chemical levels), observation may not detect chemicals, and sales data is influenced by many factors (not just chemical content).

Answer:

measuring the different levels of chemicals in samples of both bottled and tap water