Help with second blank TC using Math Strategy

What is happening between but and nevertheless in the second part of sentence according to Math Strategy?
2. What is significance of necessarily in this?

Can anyone please clear me my longstanding doubt of how two negatives work when they are side to side like in this question?

My reasoning is that if we assume latest ets format with separate options for blank 1 and 2, then can consisting fit in blank 2?

One not necessarily _____ love but nevertheless grounded in economic

So, as but means a contrast and last part says that its on economic thing then why can’t we say that it’s not on love?

As its a contrast, Question asks not this but that so adding devoid means there’s a part of love. How can we say that?

Is it because of nevertheless? Nevertheless is also contrast so, can anyone clear my doubts in terms of logic and context.

Guys @shrey.s.kulkarni @sciencenerd1609, what do you think on this?

I would go with option A.

Correct, but in sentence 2, can you share your thoughts on play between but and
nevertheless?

What is necessarily doing?