The correct answer is D. The senator's fondness for media exposure proved to be his Achilles' heel in the end.
Step-by-step explanation:
In writing and speaking, an allusion occurs when there is a reference to an external idea, person, place, situation or literary work without explaining it but just mentioning it as it is supposed the audience already known the idea the author is making reference to and therefore explaining it is not necessary. This figure of speech can be identified in the sentence "The senator's fondness for media exposure proved to be his Achilles' heel in the end" because, in this, the speaker makes reference to "Achilles' heel" which is a myth in which a Greek Hero called Achiless had only one flaw that was his heel. This means, the author only mention this but do not explain it as it is widely known by people and therefore this is an example of allusion.