The amount of exposure to radiation that a person receives is not affected by

A. Total time of exposure
B. Distance from the source
C. Degree of radioactivity of the material
D. Size or weight of the radioactive source
E. None of the above

Size or weight of the radioactive source.

Unlike  ct scans, which use x-rays,  mri scans  use powerful magnetic fields and radio frequency pulses to produce detailed pictures of organs, soft tissues, bone and other internal body structures.  differences between  normal and abnormal tissue is often clearer on an  mri  image than a  ct.you can see more with a mri scan. for example on an mri you can see internal bleeding.