Answer:
Stratovolcanoes are common at subduction zones, forming chains and clusters along plate tectonic boundaries where oceanic crust is drawn under continental crust (continental arc volcanism, e.g. Cascade Range, Andes, Campania) or another oceanic plate (island arc volcanism, e.g. Japan, Philippines, Aleutian Islands).
Weathering, plate tectonics, gulf stream, mountain roads, evaporation...
B) a fracture caused by shear stress
I’m not entirely sure what you mean. You ask for AC but give AC as 4(x+2).