The best explanation using the Circular Flow model for why lawyers generally earn much higher incomes than fast food workers is:
C. All workers sell their human capital in the resource market, and lawyers typically have more human capital than fast food workers.
This option highlights the concept that lawyers typically possess a higher level of education, specialized training, and skills (human capital) that enable them to command higher salaries compared to fast food workers, who generally require less education and training. The Circular Flow model includes the interaction between households and firms in the resource market, where the value of labor is largely determined by the skills and education workers possess.