Which person has the best qualifications to write a credible article about the rise in obesity rates among children and its association with the consumption of fast food?
 A.
 A mother whose two children often eat fast food and who are considered to be obese
 B.
 A health researcher who advocates for healthier options on fast-food menus
 C.
 A pediatrician at a children's hospital who conducted several studies on childhood obesity
 D.
 An elementary school principal who tried to ban the sale of fast food to his students