Where must each fixture be trapped with a separate trap located?

Each fixture must be trapped with a separate trap located as close as possible to the fixture outlet to effectively prevent sewer gas from entering the home and to ensure that wastewater can drain properly. Positioning the trap near the fixture allows for optimal drainage by minimizing the distance that wastewater must travel before it encounters the trap, which can help prevent blockages and maintain a clean and safe drainage system. This practice also helps in keeping the trap full of water, which serves as a barrier to protect against foul odors and gases from the sewer system.

The other options do not facilitate proper drainage or trap function. For example, placing a trap far from the fixture can lead to drainage complications and increased risk of unwanted sewer gas intrusion, while locating it in the main plumbing line or only at the base of the fixture could also compromise the system's ability to function effectively.