The correct answer is D. A concrete example is one that provides a clear situation in which the abstract idea, in this case the author's argument, is exemplified. This option not only prepares the reader for the example, but also gives specific details about what could be regulated.
Sometimes, reading things out loud can help a lot. "I had eat all the leftovers." Does that sound right? How about "I had eating all the leftovers," or "I had ate all the leftovers"? What about "I had eaten all the leftovers"?
If this doesn't work for you, think of it like this: you must always use the PAST PARTICIPLE after a form of the word "have." For example, "I had given you the present." Which of your options is most similar? Most likely, the answer is "eaten": "I confessed that I had eaten all the leftovers."
Answer: B. Eaten
The story of Damon and Pythias is an ancient Greek legend that has been retold throughout the centuries and that has been source material for many literary works. The legend expresses the ideals of friendship and examines the bond between two individuals faced with an impossible test and choice.