Answer to Question 1
The nucleus of a continent is called a craton and consists of ancient crystalline rock from which the continent grows. A continental shield is a large region where a craton is exposed at the surface. The formation of continental crust take hundreds of millions of years. It involves a sequence of seafloor spreading, leading to the formation of oceanic crust, subduction of this crust, and the remelting of it as new magma. Figure 13.5 illustrates the process.
Answer to Question 2
B