What must be present when smoke grenades are used?

The correct choice emphasizes the importance of having a firefighting device present when smoke grenades are used. While smoke grenades may serve various purposes, including training and signaling, they also produce smoke that can pose a fire hazards, especially in dry or flammable environments. The presence of a firefighting device, such as a fire extinguisher, is crucial to ensure that any accidental ignition of surrounding materials can be swiftly addressed. This proactive safety measure helps mitigate potential risks associated with the use of smoke grenades, ensuring a safer operational environment.

Other choices may relate to general safety and effectiveness in different contexts but do not specifically address the immediate fire risk that smoke grenades present. Additional personnel could enhance monitoring and support, communication devices might assist in coordination, and emergency safety gear provides personal protection, but none of these replace the necessity for a firefighting device when dealing with the potential fire hazards associated with smoke grenades.