The most accurate interpretation of how Alvarez develops the central idea across the excerpts is:
Alvarez shows how her lifelong fascination with her parents' life under the dictatorship was the basis for her writing.
This option encapsulates the progression from her childhood reflections on her parents’ experiences under the dictatorship (Passage A), to her understanding of the silence surrounding it (Passage B), and culminating in her mother's emotional response to her novel about those experiences (Passage C). Together, these passages illustrate Alvarez's evolving relationship with the history of her parents and how it inspired her creative work.