This is the best answer, because it’s the only answer that matches with the idea expressed at the end of P2: “Naomi breaks through the personal and cultural screens of silence and secretiveness that have enshrouded her past, and reconciles herself with her history.”

Kogawa, the author of Obasan, is the person who uses structure and symbols. But this question asks about Naomi, the main character of Obasan. We have no reason to think Naomi uses structure and symbols.

We know that the transformation into hero occurs toward the end of a character’s journey. Naomi’s relationship with her surrogate family begins in the middle of her journey. We’re looking for an answer that describes the end of Naomi’s journey — the part where she “breaks through the personal and cultural screens of silence and secretiveness that have enshrouded her past, and reconciles herself with her history.”

Naomi’s religious beliefs are not discussed in connection with her heroic transformation.

It’s not clear that Naomi denounced the majority culture. Kogawa, the author of Obasan, denounced the majority culture.