Why is a new volcano growing out of the Krakatoa crater?

The lines marked by the letters a, b, and c on the map above represent a. chains of volcanoes b. earthquake fault lines c. thin strips of heavy forests d. major rivers that flow from north to south

The covers all of earth like a thin shell,but it is not a solid sheet of material.it is broken up into several large sections and many smaller ones. fill in the blank.

What could the united states of america do to improve their status? name at least 3(ap human geography)