Although Cara has been obese for as long as she can remember, she is determined to lose excess body weight with a low-calorie diet. Cara is most likely to have difficulty becoming and staying thin because: A) she may have a higher-than-average set point for body weight. B) fat cells can be lost only with vigorous exercise. C) the number of calories a person consumes daily has no effect on body weight. D) lean tissue is maintained by fewer calories than is fat tissue. E) her resting metabolic rate will increase and prompt her to ov