Please choose the correct answer to the question: Red-clay bricks have a density of approximately 2000 kg/m^3. Air has a density of 1 kg/m^3. Which of the following has the lowest mass?

Answer1: 2 m^3 of bricks Answer2: 4 m^3 of bricks Answer3: 6000 m^3 of air Answer4: 10,000 m^3 of air

Answer format: answer1/answer2/answer3/answer4