<span>Assuming that this is referring to the same cartoon that was posted before with this question, its purpose is to "</span>support nativist anti-immigration sentiment" since it paints immigrants in a bad light.
<span>This quote suggestions that "Americanization", rather than a form of assimilation into a homogeneous culture as some would have it appear to be, is in fact an act which has been in a state of national evolution since even the early days. Indeed, the influence of the Catholic immigrants upon the incumbent Anglo-Saxon protestant culture indicates one of the very earliest instances of this evolutionary shift.</span>
D. Lack of a clearly designated successor to the imperial throne. During the decline of the empires, the succession of the throne became a contest between family members. Hope this helps.