What of These Is the Setup in the Current Design

What of these is the setup in the current design of a Co-60 unit, which is used to administer radiation in radiation therapy?

A) The radiation source is placed in a spot called the isocentre, from which the radiation beam is aimed at the patient.
B) The part of the patient's body where the tumour is located is placed in the isocentre, around which numerous sources of radiation are arrayed in a circle, administering radiation from various angles.
C) The part of the patient's body where the tumour is located is placed in the isocentre.The treatment head with a single source of radiation rotates around the isocentre, administering radiation from various angles.
D) The radiation source is placed in a spot called the isocentre, from which the treatment head goes back and forth toward the patient, administering radiation from various angles.