Explanation:
High Availability

The SLA for virtual machines guarantees 'uptime'. The amount of uptime guaranteed depends on factors such as whether the VMs are in an availability set or availability zone if there is more than one VM, the distribution of the VMs if there is more than one or the disk type if it is a single VM.
The SLA for Virtual Machines states:
For all Virtual Machines that have two or more instances deployed across two or more Availability Zones in the same Azure region, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.99% of the time.
For all Virtual Machines that have two or more instances deployed in the same Availability Set or in the same Dedicated Host Group, we guarantee you will have Virtual Machine Connectivity to at least one instance at least 99.95% of the time.
For any Single Instance Virtual Machine using Premium SSD or Ultra Disk for all Operating System Disks and Data Disks, we guarantee you will have Virtual Machine Connectivity of at least 99.9%.
References:
https://azure.microsoft.com/en-us/support/legal/sla/summary/
https://azure.microsoft.com/en-us/support/legal/sla/virtual-machines/v1_9/

Explanation:

Azure policies can be used to define requirements for resource properties during deployment and for already existing resources. Azure Policy controls properties such as the types or locations of resources.
Azure Policy is a service in Azure that you use to create, assign, and manage policies. These policies enforce different rules and effects over your resources, so those resources stay compliant with your corporate standards and service level agreements. Azure Policy meets this need by evaluating your resources for non-compliance with assigned policies. All data stored by Azure Policy is encrypted at rest.
Azure Policy offers several built-in policies that are available by default. In this question, we would use the
'Allowed Locations' policy to define the locations where resources can be deployed.
References:
https://docs.microsoft.com/en-us/azure/governance/policy/overview

Azure Key Vault is a secure store for storage various types of sensitive information including passwords and certificates.
Azure Key Vault can be used to Securely store and tightly control access to tokens, passwords, certificates, API keys, and other secrets.
Secrets and keys are safeguarded by Azure, using industry-standard algorithms, key lengths, and hardware security modules (HSMs). The HSMs used are Federal Information Processing Standards (FIPS) 140-2 Level
2 validated.
Access to a key vault requires proper authentication and authorization before a caller (user or application) can get access. Authentication establishes the identity of the caller, while authorization determines the operations that they are allowed to perform.
References:
https://docs.microsof t.com/en-us/az ure/key- vault/key-vault-overview