Intellectual disability refers to the disability of the mental functions which are characterised by the low or limited approach to thinking, learning, reasoning and the problem solving abilities.
The intellectual disability also involves the limitations in the adaptive behaviour which interfere with the social learning and skills.
The etiology term is used by the doctors to know the origin of the way the things are now. The etiological perspective fro intellectual disabilities therefore is the result of wither the biological defects in the brain or some disease.
Thus, Etiological perspective is the correct answer.
ATP is what powers energy for cell's and when you take a phosphate group away you are left with ADP. ADP doesn't carry as much power as ATP does. Hope This Helps:)