B uses radiation so I would assume it would be the one using x rays
Answer: Subarachnoid
Explanation:
The space in the meninges below the arachnoid membrane and above the pia mater contains the cerebrospinal fluid. Cerebrospinal fluid is produced by choriod plexus( a cluster of capillaries) from the blood. Blood vessels traveling within the subarachnoid space deliver oxygen and nutrients to the spinal cord.
Atom is the basic element of all living things because it's small. It is the smallest constituent unit of matter which has the properties of a chemical element. They are very small. Sizes are about 100 or 100, 000 fm. They are unstable. They are composed of a nucleus and electrons.