Let us look at this question this way. Use of past perfect is essentially a chronological factor, when two events that started and ended in the past are to be marked with proper tenses. In this scenario, the one that is clearly the earlier, will be in past perfect and the one that is later in simple past. . Supposing there were more than two event the last of one of the series of action will entail a simple past tense, while the all the previous ones will entail use of past perfect.
Thus, to cite an example,
1. I
had woken up pretty late in the morning and
darted to the office like a bullet.
Only two events and hence the last one is in simple past and the earlier one is in past perfect.
2. I
had woken up, pretty late,
taken bath quickly,
eaten my breakfast in a gulp and
darted to the office like a bullet.
More than two events, only the last one in simple past and all the other earlier ones, though more than one, marked in past perfect.
Now to come to the question, the order of chronology is this:
1. First, Beethoven revolutionized classical music ete, etc. This is the earlier event. and so needs a past perfect-
had revolutionized 2. Then by the time of Fidelio, it became clear…… etc, etc. This “becoming clear” is the later event and in this case the last event, because there are only two events. Hence proper grammar usage requires that the earlier Beethoven’s act be marked in past perfect, while, the later “becoming clear”, be marked in simple past, i.e
became clear How can in that case E be the right answer, with the use of “had become clear.” a past perfect for the last event? Only A can be the right answer IMO. In general, unless there is a simple past, there can not be a past perfect. In other words, the legitimacy of a past perfect is derived from the use a simple past.; Like in Arithmetic, there may any number of zeroes but they all gain strength only when at least a single 1 is there among them. Similarly there can be any number of past perfects but they all become valid when there are accompanied by a simple past.
Our example violates this vital aspect. Hence IMO, E is ungrammatical and I am not convinced about it veracity Please re-check
I am citing the general position on the use of past perfect tense. There may still be some odd examples here and there, thrown up by some bard under some poetic license or some Bertrand Russells under some literary license that violate this grammar. But they are exceptions rather than rules.
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