Developed nations have a vested interest in the health of less developed nations whenever which of the following can travel from less to more developed nations?

A) air pollution
B) diseases
C) workers
D) all of the above
E) none of the above

All the options mentioned in A, B, and C can travel from less developed nations to more developed nations. Air pollution can spread through wind patterns, diseases can be transmitted through infected individuals or contaminated products or food, and workers can migrate from less developed nations to more developed nations in search of better job opportunities. Therefore, developed nations have a vested interest in the health of less developed nations to prevent or mitigate the adverse effects of these potential threats.