The technique being used is Positron Emission Tomography. The PET scanner will measure the amount of positrons that collide with the electrons in the brain, and this data will then be analyzed using a computer program that generates a color map of activity in the brain. These colors range from purple (little to no activity) to red (high or very high activity).
Answer:
I believe your first two are correct but your bottom two should be rearranged. Have you tried looking it up?
Explanation:
The answer is four. ,,,,,