Look at the symbol. Which component in a circuit does it represent? A.
conductor
B.
AC power source
C.
DC power source
D.
switch

On page number 2 for the question number 7 is answered by Oceanic-continental convergent plate boundaries expect that 1 plate is continental. Since oceanic crust has density of 3g/cc and continental crust has a density of only 2.7g/cc whenever oceanic crust collides with continental crust the oceanic crust subducts