The answer to this is a bit simple it would be B. X-ray scanners, because doctors use x-rays to tell when a bone is cracked, splintered, or broken.
The best answer i can find are Protozoa Ricketts
Although Ricketts are a disease, ever source i can find claims it's the answer.
"A medicine taken or given to counteract a particular poison"
-Hazard mapping
-Adoption and enforcement of land use and zoning practices.
-Implementing and enforcing building codes.
-Flood plain mapping.
-Reinforced tornado safe rooms.
-Burying of electrical cables to prevent ice build-up.
-Raising of homes in flood-prone areas.