Gmatclub test sc question

Where is this question from?

To me all the answer choices are wrong, because you need London after the comma (not a blitz or a refusal as a subject), since "having been bombed" refers specifically to London.

I totally agree with you. Having been bombed should refer to the subject London not to London's refusal. Bad question.

I totally agree with you buddies.
The only problem is that this test question is from free https://gmatclub.com/tests/.
May be one of GURUs will help to see pitfall in this question?

Thank you for bringing this up. Let me check with Emily (esledge) about the question - she is an expert in verbal.
_________________

The posters are all correct: London (not London's something) must follow the modifier "having been bombed..."

It seems to me that this question intends to test two concepts: (1) the idiom "took on" and (2) the choice of a subject noun (or nouns) that could logically take on "... mythic significance." The existing explanation for (A) alludes to the misplaced modifier, the same explanation we should find for all the other choices! Also, I think the real GMAT might take issue with "it" in the original sentence. I think the antecedent of "it" is reasonably clearly "the Blitz," but I find "after it" to refer to an event a bit unidiomatic. You could leave "it" in, as it provides yet another reason the original is not best, but here's what I'd propose to fix this question:

Though the city had been bombed for fifty-seven nights in a row, the Blitz and the refusal to surrender London afterward took on almost mythic significance as evidence of British citizens’ ability to resist the will of Hitler and Nazi Germany.

(A) the Blitz and the refusal to surrender London afterward took on

(B) London’s Blitz and the refusal to surrender took after

(C) the Blitz and the refusal of the city of London took over

(D) London’s refusal to surrender after the Blitz took on

(E) London’s refusal to surrender after the Blitz took up