Answer: an Azure data center failure

Azure Availability Zones are designed to protect against data center failures within an Azure region. Each Availability Zone is a physically separate location with independent power, cooling, and networking. According to Microsoft documentation and the strong community consensus (with 100% agreement and high upvotes on comments confirming this), Availability Zones specifically address data center-level failures. While some comments noted that physical server failures (A) and storage failures (C) might also be mitigated indirectly since they occur within data centers, the primary and explicit purpose of Availability Zones is data center failure protection. Option B (Azure region failure) is incorrect because Availability Zones operate within a single region and do not protect against regional outages, which require geo-redundant solutions.

Author: LeetQuiz Editorial Team