Strengthening Dietary Claims on Life Satisfaction

Researchers conducted an analysis on the dietary habits of individuals in urban areas. They found that those who consumed more fruits and vegetables tended to report higher levels of satisfaction with life. This correlation prompted discussions about the potential benefits of a healthier diet on overall well-being. However, it was also noted that these individuals often engaged in other health-promoting behaviors, such as regular exercise and socializing more, which might also contribute to their life satisfaction.

To strengthen the argument that a diet rich in fruits and vegetables directly leads to higher life satisfaction, which of the following statements would be the most effective?