Finish parent and current activity in Android

Question

I have 3 activities. Activity A which leads to activity B, which in turn can go back to activity A or start activity C. However, if I press back in activity C the app should

Answer 1

Intent intent=new Intent(ActivityB.this, ActivityC.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);

your activity C will the root activity and on press back will finish the apps.