Automatic Tube Current Modulation Is a Method

Automatic tube current modulation is a method
1) to reduce patient exposure
2) to improve image quality
3) similar to automatic exposure control

A) to reduce patient exposure and to improve image quality only
B) to reduce patient exposure and similar to automatic exposure control only
C) to improve image quality and similar to automatic exposure control only
D) to reduce patient exposure, to improve image quality, and similar to automatic exposure control