According to Your Textbook,why Do Some Researchers Question the Role

According to your textbook,why do some researchers question the role of a physiological set point being responsible for the difficulty some people have when trying to lose excess weight?

A) The body's metabolic rate is fixed and does not change.
B) The difficulty in losing excess weight is greatly exaggerated.
C) Lower activity levels appear to be able to explain the difference.
D) Set point theory assumes that a person's set point cannot change.