Which of the following is a category of requirements for alerting techniques?

The correct answer encompasses all options, as each one represents a legitimate category of requirements for alerting techniques within the context of NFPA 70E.

Attendants are individuals designated to oversee electrical work and provide immediate assistance or warnings to those in proximity to electrical hazards. Their presence serves as an alerting technique, ensuring that workers are aware of potential dangers.

Barricades are physical barriers employed to restrict access to hazardous areas. By clearly delineating unsafe zones, barricades function as a visual cue to alert individuals that hazards may exist beyond the barrier, urging them to stay clear of the area.

Safety signs and tags are crucial for communicating important information regarding electrical hazards. They provide vital warnings and instructions that inform workers of the risks involved and the necessary precautions to take when working in or near energized equipment.

By including attendants, barricades, and safety signs and tags, this answer highlights a comprehensive approach to alerting techniques, affirming the importance of each element under the NFPA guidelines for maintaining safety in electrical work environments.