Permanent loss of records that triggers regulatory breaches and audit failures is the correct answer.

This is the primary hazard because required backups and retention copies are often legal or regulatory obligations. If those copies are not preserved the records can become irretrievable and the organization can face compliance penalties, failed audits, litigation risks, and loss of evidence needed for investigations.

Residual permissions or misconfiguration that increase the chance of data exposure is not the best choice because that issue describes access control weaknesses and potential data leaks. The question asks about the main hazard from failing to preserve backups and retention copies and that is the permanent loss of records and compliance failure rather than leftover permissions.

Unexpected rise in storage and retention costs from keeping obsolete backups is incorrect because decommissioning systems normally reduces storage costs. The scenario is about not preserving backups and retention copies and the major risk there is losing required records not incurring higher retention costs.

Temporary reduction in network throughput during shutdown and migration tasks is wrong because throughput impacts are operational and short lived. The core concern when backups and retention copies are not preserved is a lasting loss of records with regulatory and audit consequences and not a transient performance degradation.

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