I think it’s a - it doesn’t use radiation
Treating a person's mental disorders will reduce suicide risk.
All of the other options can be dangerous for those suffering from depression or who are suicidal.
I believe you are asking about the "triangle" we were tought a simple triangle. Cells at the bottom because there are the most of them, tissues next, organ next, and organ system at the top. So I believe the answer you are looking for is Organ System.
In every industry, people or employees are exposed to different kinds of hazards. These harm their body, health, the surroundings, etc. Hierarchy of hazard control is a system that would allow industry to minimize or not eliminate these hazards.
In the hierarchy, what comes before the PPE are the Engineering Controls, which ensures that the design is suited for the purpose, and, Administrative Controls, in which people should be taught on how work should be done and the underlying safety principles.
