Three copies across three availability zones in the primary region is correct.

Zone Redundant Storage places three synchronized replicas of your data across separate availability zones within the primary region to provide resilience to zone failures and to ensure high availability. This configuration results in three total copies distributed across zones rather than copies per zone or additional replicas in a secondary region.

Three copies stored in each availability zone is incorrect because that interpretation would yield nine replicas in total and ZRS only maintains three replicas across the zones, not three per zone.

One copy is incorrect because ZRS is a redundant storage option that intentionally keeps multiple synchronized replicas to tolerate hardware and zone failures, so a single copy would not meet that guarantee.

Six total replicas is incorrect for ZRS because six replicas describe geo redundant patterns such as GRS which store three copies in the primary region and three in a secondary region, while ZRS keeps three copies only in the primary region.

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