After the servicing of a septic tank, it is essential that the tank or lid be:

The correct choice emphasizes the importance of safety following the servicing of a septic tank. After servicing, it is crucial that the tank or lid is replaced and secured to prevent accidents, contamination, or unwanted access. A properly secured lid ensures that children, animals, or unauthorized persons cannot fall into or tamper with the septic system, reducing the risk of injury or death. Additionally, a well-fitted lid helps prevent the escape of odors and the entry of surface water, which could compromise the tank's function and lead to failures.

In the context of maintaining sanitary conditions and local health standards, ensuring that the septic tank is duly secured reflects best practices in public health and safety management. This step is vital in protecting both the environment and community health.