A: 7 - ui/example_2/Example2Activity.java

Example2Activity.java

public final class Example2Activity extends BaseActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.example_2_activity);

        if (savedInstanceState == null) {
            addFragment(R.id.fragment_a_container, new Example2AFragment());
            addFragment(R.id.fragment_b_container, new Example2BFragment());
        }
    }
}