What common safety measures should be taken in areas where radioactive materials are used?

The correct answer highlights essential safety measures critical for environments where radioactive materials are utilized. Signage is vital as it alerts personnel and visitors to the presence of radiation hazards, helping to ensure awareness and caution in these areas. Training is equally important because it equips individuals with the knowledge and skills needed to work safely with radioactive materials, understand the risks involved, and respond adequately in emergency situations. Proper barriers are crucial for physical protection; they help to contain radioactive materials and reduce exposure risk by separating these materials from individuals who do not require access.

In contrast, the other options compromise safety and do not align with established radiation protection protocols. Extended shifts can lead to fatigue, increasing the risk of accidents and misjudgments in handling radioactive materials. Limited training would leave workers unprepared to manage safety properly. Isolation without signage can create a false sense of security and may lead to unintentional exposure, while minimal supervision increases the chances of unsafe practices going unnoticed, further heightening the risk of accidents. Thus, the correct choice emphasizes the comprehensive safety culture required in environments involving radioactive materials.