Libby's physician refers her to a medical center in order to have the biochemical activity in her brain analyzed. she is given an injection of a radioactive glucose-like substance and then is told to lie down with her head in a scanner. the technique being used is

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).

The answer would be a (carbohydrates)