Cases heard by the supreme court under its appellate jurisdiction arrive there because:

answer; (a) he was a u.s senator for 38 years;

interdependence is when all participating groups and individuals depend on each other. if you depend on one anothers goods, you end up trading in order to get the items you're looking for. (for ex: if i have food and you have water, we trade in order to depend on each other to live)