Which of the Following Best Reflects Psychology's Goal of Influence

Which of the following best reflects psychology's goal of influence?

A) Researchers have examined hundreds of cases of dissociative identity disorder (multiple personality) order to provide a clear picture of the disorder.
B) Researchers have studied how smoking habits develop so that they may develop techniques to prevent teenagers from starting the habit
C) Researchers have developed a test that shows whichdividuals are likely to develop Alzheimer's disease.
D) Researchers have identified a genevolved many cases of obesity.