Epigenetics, methylation graph

Hi, I couldn’t understand this question related to epigenetics, can someone please explain why the answer of this is option D?

Source: IB May 2016

Hi, too late but might be helpful for anyone :

There is no way it is option C because it is saying the patterns are not shown before fertilization while the patterns are right in front of us. Fertilization btw is the point where maternal and paternal DNAs met. And before this intersection point there were patterns so C is eliminated

Then B is telling you maternal got demethylated first? well no because maternal was never demethylated in first place, it was only methylated. the paternal dna however, after it dropped, started rising again. so B is also eliminated

A is saying only the paternal, but in fact the methylation of the embryo is now attached to the methylation of the female. so when you see the embryonic DNA started rising after severely dropping, this indicated a demthylation in the embryonic DNA AND in the maternal DNA

option D, the final one, states that the patterns were erased after fertilization, well this is true the individual patterns were erased and we saw the “combination” of these patterns in the embryonic.

My deducation might have been wrong but this is how i solved it during my exam and voila it was correct

Have a nice day!

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