Final answer:
Qualified personnel are those trained or certified to repair equipment and assure its safety for use. They can be technicians, engineers, safety officers, or others with specialized expertise.
Step-by-step explanation:
The individual who is qualified to repair equipment and determine that it is safe to use is D. Qualified personnel. This term often refers to individuals who have received special training or certification that allows them to understand and manage the specific risks associated with different types of equipment. They will have the knowledge to not only repair the equipment but also to assess its safety for use post-repair. In some cases, this could be a certified safety officer, an engineer, a technician, or another individual with the requisite skills and authorization defined by industry standards, regulations, or company policies.