All of the Following Are Advantages of FMRI Over PET

All of the following are advantages of fMRI over PET imaging EXCEPT fMRI:

A) is a noninvasive procedure and the magnetic waves are harmless allowing research participants to undergo repeated fMRI scans.
B) produces a sharper image than PET scans and therefore can detail much smaller brain structures.
C) is that it provides a picture of brain activity averaged over seconds rather than the several minutes required by PET scans.
D) involves the use smaller amounts of radioactively tagged glucose or oxygen than does PET.