Doctor: It would benefit public health if junk food were taxed. Not only in this country but in many other countries as well, the excessive proportion of junk food in people' s diets contributes to many common and serious health problems. If junk food were much more expensive than healthful food, people would be encouraged to make dietary changes that would reduce these problems. Which one of the following most accurately expresses the conclusion drawn in the doctor's argument? ['Taxing junk food would benefit public health.', 'Junk food should be taxed if doing so would benefit public health.', "In many countries, the excessive proportion of junk food in people's diets contributes to many common and serious health problems.", 'Taxing junk food would encourage people to reduce the proportion of junk food in their diets.']