Final answer:
The cracking and ripping sound heard as the House of Usher collapses underscores the finality of the Usher family's decline.
Step-by-step explanation:
The significance of the "cracking and ripping sound" heard as the House of Usher collapses is c) It underscores the finality of the Usher family's decline. This sound serves as a symbolic representation of the irreversible destruction and collapse of the Usher lineage. It emphasizes the end of an era and the ultimate downfall of the Usher family.
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