Why Should the Selection of Technical Exposure Factors for All

Why should the selection of technical exposure factors for all medical imaging procedures always follow ALARA?

A) So that referring physicians ordering imaging procedures do not have to accept responsibility for patient radiation safety.
B) So that radiographers and radiologists do not have to accept responsibility for patient radiation safety.
C) Because radiation-induced cancer does not appear to have a dose level below which individuals would have no chance of developing this disease.
D) Because radiation-induced cancer does have a dose level at which individuals would have a chance of developing this disease.