What must all security officers wear while on duty?

All security officers are required to wear company-issued uniforms that are clearly identifiable as security personnel. This requirement serves multiple purposes. Firstly, identifiable uniforms help establish the authority and presence of security personnel in any environment, which is essential for maintaining order and ensuring the safety of the public. When individuals can easily recognize a security officer, it fosters a sense of security and allows for quicker response times in emergencies.

Additionally, uniforms promote professionalism and convey a standardized appearance that aligns with the organization's branding and standards. This consistency is important in building trust with the patrons or clients security officers serve, as it signifies that the individuals are trained and authorized to handle security-related matters.

The other options, such as wearing civilian clothes for discretion or casual attire to appear approachable, may undermine the effectiveness of a security officer’s role, as these approaches can lead to confusion about authority and responsibilities. Costumes, while potentially used in special contexts, do not serve the practical purpose of identifying a security officer in a standard situation, which is essential for the role they play.