Which of the following best defines a controlled area in radiation safety?

A controlled area in radiation safety is specifically defined as a designated space where radiation levels are monitored and controlled to protect individuals from exposure. This definition encompasses areas where stringent safety protocols are implemented to ensure that people working or present in those areas are trained to recognize and handle radiation hazards.

In this context, the definition aligns closely with the first choice, which emphasizes the importance of having individuals who are educated about radiation safety within those controlled spaces. These trained individuals can respond appropriately to potential radiation risks, implement safety measures, and maintain a safe environment.

While wearing radiation monitors and having an occupancy factor of 1 can also be relevant aspects of controlled areas, the core definition prioritizes the training and expertise of individuals present. Hence, the correct option highlights the essential element of training in radiation safety, making it the best answer.