What type of system can be used for transferring fuel oil?

The correct choice outlines that an automatic pump can be used for transferring fuel oil. This method is widely accepted because it enables efficient and safe transfer of fuel oil from one location to another, often automating the process to reduce the chance of spills or hazards that can arise from manual transfer methods. Automatic pumps ensure that the correct flow rates and pressures are maintained, which is crucial for safety and compliance with mechanical codes.

Using an automatic pump can also help in managing the transfer in a more controlled manner, reducing the potential for human error, which can occur with manual systems. Furthermore, this type of system can be designed to meet various safety and regulatory standards.

In comparison, gravity feed systems alone can introduce potential hazards, such as unregulated flow and spills, thus are less preferred in many applications. While manual systems may be used, relying solely on them may not provide the efficiency or safety levels that an automatic solution can. Any unapproved method would not be compliant with established safety standards, posing risks to both the operator and the environment.