14. All of the following are advantages of fMRI over PET imaging EXCEPT: A) fMRI is a noninvasive procedure and the magnetic waves are harmless, allowing research participants to undergo repeated fMRI scans.

B) fMRI produces a sharper image than PET scans and therefore can detail much smaller brain structures.

C) fMRI provides a picture of brain activity averaged over seconds rather than the several minutes required by PET scans.

D) fMRI involves the use of smaller amounts of radioactively tagged glucose or oxygen than does PET.