Final answer:
Jackie, with anorexia nervosa, is most likely competitive and high-achieving due to the condition's link with perfectionism and the cultural pressures to maintain a thin appearance commonly found in Western society.
Step-by-step explanation:
Jackie, a 15-year-old girl diagnosed with anorexia nervosa, is most likely C) competitive and high-achieving. Individuals with anorexia nervosa tend to have a distorted body image, often viewing themselves as overweight even when they are underweight. This stems from a combination of environmental factors, such as the cultural idealization of thinness, and possibly genetic predispositions. It's a condition that is frequently associated with high levels of personal achievement and perfectionism, which can contribute to the competitive and high-standard setting nature of those affected.
While the question suggests different options, the idea that Jackie sets very low standards for herself or is not concerned about others' perceptions does not align with the typical psychological profile of someone with anorexia nervosa. Moreover, while anorexia nervosa can occur across all ethnic and socioeconomic groups, the higher prevalence rates have been noted predominantly among White females from Western societies, therefore option D) is less statistically likely.