You need to identify the type of failure for which an Azure (AZ-900)

Correct answer: D) An Azure data center failure.
Here's why:
Azure Availability Zones are a feature designed to protect against failures within a specific Azure region.

Let's break down the options:
A physical server failure: While Availability Zones can help mitigate the impact of a server failure within a zone, they are not designed to protect against it directly. Azure's infrastructure is designed with redundancy at the server level, so a single server failure is typically handled automatically.
An Azure region failure: This is the primary scenario Availability Zones are designed to protect against. If an entire Azure region experiences an outage, your applications deployed across Availability Zones within that region will continue to function from the unaffected zones.
A storage failure: Storage failures are handled by Azure's storage redundancy features (like geo-replication) rather than Availability Zones.
An Azure data center failure: Availability Zones are built across multiple, independent data centers within a region. This means if one data center fails, your applications running in other data centers within the same Availability Zone will remain operational.