What action is recommended after a fire is extinguished by a subway employee?

Informing the Fire Department of the incident is crucial because, even after a fire is extinguished, there may still be residual hazards or safety concerns that need professional assessment. The Fire Department has the expertise and resources required to evaluate the scene thoroughly, ensuring that there are no lingering dangers such as smoldering materials or potential structural damage. Additionally, they can assist in determining whether the fire was due to an underlying issue that needs to be addressed to prevent future incidents. This step not only ensures the safety of personnel and bystanders but also contributes to proactive measures in fire prevention and safety management.

The other options may not prioritize the critical need for professional oversight in such situations, which could lead to unsafe conditions if not properly managed.