I chose E, but now see why the answer is C.
For many people, household labor remains demanding even if able to afford household appliances their grandparents would find a miracle.
(A) even if able to afford household appliances their grandparents would find a
miracleadjective required as modifying the appliances.(B) despite being able to afford household appliances their grandparents would find a
miraclesame as A, also use of 'being able to' rather than 'can'. Also changes the meaning that all can afford(C) even if they can afford household appliances their grandparents would have found miraculous
I couldn't catch at first that 'their grandparents would have found miraculous' is modifying the appliances.(D) although they could afford household appliances their grandparents would find miraculous
changes the meaning - not all can afford.
(E) even if they are able to afford household appliances which would have been a miracle to their grandparents
'can' is preferred to 'are able to'
'which ...' is wordy as compared to C.
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Consider kudos for the good post ... 
My debrief : journey-670-to-720-q50-v36-long-85083.html