Julianna is a nine-year-old child diagnosed with attention deficit hyperactivity disorder. Her mother was a chain smoker even after Julianna was conceived. Which of the following factors is chiefly responsible for her condition?A. Julianna has one form of a dopamine gene but not the other.B. Julianna has abnormal brain growth rate.C. Julianna consumed excess amounts of sugar as an infant.D. Julianna inherited both forms of a dopamine gene from her mother.E. Julianna has one form of a dopamine gene but not the other