Libby's Physician Refers Her to a Medical Center in Order

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

A) positron emission tomography.
B) functional magnetic resonance imaging.
C) microelectrode recording.
D) an electroencephalogram.
E) an electromyography.