How have pet scans contributed to our understanding of the brain and abnormalities?

a positron emission tomography (PET) scan is an imaging test that allows your doctor to check for diseases in your body. The scan uses a special dye containing radioactive tracers. These tracers are either swallowed, inhaled, or injected into a vein in your arm depending on what part of the body is being examined

answer; i do believe that the correct answer is (b)

obviously, the latter.