Sentence Correction (SC) | Having been forbidden by Church law to marry, it was not unusual for

Can someone please explain the flaw in A,B and D.

C is clearly wrong -

(C) Although' they' were forbidden by Church law to marry, it was not unusual for 'a priest' during the Middle Ages to sire a family.

(E ) looks perfect , but I wanted to clearly understand the flaw in a,b and d.

(A) Having been forbidden by Church law to marry, it was not unusual for a priest during the Middle Ages to sire a family. - Might be wrong because 'having' here is not clearly modifying the subject of the sentence.

(D)
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