Final answer:
Among the given options for common indoor air pollutants, dihydrogen monoxide vapor, which is simply water vapor, is not considered a pollutant, making it the correct answer to which is not a common indoor air pollutant. the Correct option is A.
Step-by-step explanation:
The common indoor air pollutants include radon gas, which is a radioactive substance that can seep through building foundations; mold, which can cause allergic reactions and asthma attacks; volatile organic compounds (VOCs), which are chemicals that off-gas from products such as paint and can cause health issues; and asbestos, which was commonly used in building materials in the past and can cause cancer. However, dihydrogen monoxide vapor is just a scientific term for water vapor and is not typically considered an air pollutant. Therefore, the correct answer is option a) Dihydrogen monoxide vapor, which is not a common indoor air pollutant.