The easiest way to answer this question is to think logically not poetically. Let’s be real here, the first two and last options don’t even sound figurative so it’s obviously the third option “c”.
If do want a real answer from me, “a caged bird stands on the grave of dreams” pretty much sums up the fact that the birds dreams were shattered and his hope was destroyed. His wings were also clipped and feet were tied meaning that he lost his freedom and hope because he couldn’t fly.
Interpreting the sentence we can say that the resigning of the individuals shows that it is not necessary. It is not the definition of resigning. There is no contrast, as well. This sentence just shows the restatement of the given idea. Restatement is saying something in a different way in which the author uses it here for the word "resigning".
