Explanation
A private cloud is hosted in your datacenter. Therefore, you cannot close your datacenter if you are using a private cloud.
A public cloud is hosted externally, for example, in Microsoft Azure. An organization that hosts its infrastructure in a public cloud can close its data center.
Public cloud is the most common deployment model. In this case, you have no local hardware to manage or keep up-to-date everything runs on your cloud provider's hardware.
Microsoft Azure is an example of a public cloud provider.
In a private cloud, you create a cloud environment in your own datacenter and provide self-service access to compute resources to users in your organization.
This offers a simulation of a public cloud to your users, but you remain completely responsible for the purchase and maintenance of the hardware and software services you provide.
https://docs.microsoft.com/en-gb/learn/modules/principles-cloud-computing/4-cloud-deployment-models

Explanation
Authentication, not authorization is the process of verifying a user's credentials.
The difference between authentication and authorization is:
* Authentication is proving your identity, proving that you are who you say you are. The most common example of this is logging in to a system by providing credentials such as a username and password.
* Authorization is what you're allowed to do once you've been authenticated. For example, what resources you're allowed to access and what you can do with those resources.

Explanation

Explanation
You are not charged for unused network interfaces. Therefore, deleting unused network interfaces will not reduce the Azure costs for the company.
References:
https://docs.microsoft.com/en-us/azure/advisor/advisor-cost-recommendations#reduce-costs-by-deleting-or-recon

Explanation