Which of the following can be classified as special units that may be called to the scene?

Special units that can be called to the scene in emergency situations typically consist of specialized teams capable of addressing unique or complex scenarios. While all the entities listed have important roles in a wide range of emergencies, military units are often classified as special units due to their specialized training, advanced resources, and tactical capabilities that can be deployed during situations requiring specialized intervention, such as hostage situations or natural disasters.

Medical personnel provide medical assistance and care during emergencies, while the fire department is crucial for handling fire-related incidents and rescue operations. Local law enforcement is essential for maintaining order and conducting investigations at a scene. However, these entities don't generally maintain the same specialization level for tactical or strategic operations that military units do. Hence, in the context of special units, military forces would be the most appropriate classification as they are often equipped and trained for unique operational roles that go beyond standard emergency response functions.