Who is likely to be affected by a chlorine leak from a gas cylinder?

The correct choice highlights that laborers, port workers, and fire fighters are likely to be directly affected by a chlorine leak from a gas cylinder due to their proximity and involvement in handling or responding to hazardous materials. Chlorine, being a toxic gas, poses significant risks to individuals who are in the vicinity of the leak, particularly those who are actively working in environments where chlorine is stored, transported, or used.

Laborers and port workers often operate in areas where chlorine gas may be present and are therefore more vulnerable to exposure during a leak. Fire fighters, on the other hand, are first responders who may be called to manage the situation. They require specialized training to handle hazardous material incidents safely and effectively.

In contrast, the other options limit the group of individuals who might be affected inappropriately. An office worker may not be in immediate danger unless they are located very close to the site of the incident. Nearby residents may face risks as well, but they are not specifically involved in the direct handling of hazardous materials, and environmental agencies primarily respond after the fact rather than being directly affected in real time. Thus, the most likely individuals to experience direct consequences from such a leak are those actively engaged in related professions.