Keshav1404The meanings of C and E (before the comma) are basically identical. Adverbial modifiers have some flexibility in their placement, so if I "try to do this later" or "try later to do this," it's the same. There would only be a difference if I were emphasizing that I *only* wanted to do something later: "I will try to do this LATER if I can, because I'd like to avoid doing it now." That's not really an issue here, so we don't have to worry much about those word order differences in C/E.
What makes E work and C fail is that we are trying to modify a modifier. We have an achievement. What achievement? One THAT kings attempted to repeat. (THAT indicates the beginning of our noun modifier.) E correctly adds detail to that modifier with an adverbial modifier ("but without success"). C proceeds as if we have just read a normal clause, and now we are adding a parallel verb. We could say "other kings attempted this but were not successful." But that's not what we have! Since "THAT other kings . . . " is a modifier, the whole thing applies to the noun ACHIEVEMENT. So on top of everything else, adding "at it" at the end is redundant.
In short, don't use constructions like this:
She made a movie that many people watched, and were intrigued by it.Cut the comma and IT: "that many people watched and were intrigued by." Notice that now the two verbs (watched, were) are parallel. The people are the subject and the movie is the object. Adding IT made a repeat object, and we don't want that! ("This is a movie that I like it." No!)
There were several shirts that I liked, but didn't buy them. We can fix in the same way by leaving off THEM and the comma. (Now LIKED and DIDN'T BUY are parallel verbs.) In this case, there's also an even easier fix. We could make two complete clauses by simply repeating the subject: "I didn't buy them." Now we two clauses joined with a comma and a conjunction.