Under which of the following cloud computing models would the Azure "Content Delivery" service fall into?

Answer options:

A.Infrastructure as a service (IaaS)
B.Platform as a service (PaaS)
C.Software as a service (SaaS)
D.Function as a service (FaaS)

Answer – B 
The Platform for hosting Azure CDN is managed completely by Azure. Below is the description of the service from the Microsoft documentation. 

Storage is very important in Azure. Without storage then Azure would not exist. There are several different aspects of storage that we need to understand. We look at each of these different concepts. Things like the storage account, replication, lift/shift and so much more. 
Azure Content Delivery Network (CDN) is a global CDN solution for delivering high-bandwidth content. With Azure CDN, you can cache static objects loaded from Azure Blob storage, a web application, or any publicly accessible web server,by using the closest point of presence (POP) server. 
A content delivery network (CDN) is a distributed network of servers that can efficiently deliver web content to users. CDNs store cached content on edge servers in point-of-presence (POP) locations that are close to end-users, to minimize latency. 
Azure Content Delivery Network (CDN) offers developers a global solution for rapidly delivering high-bandwidth content to users by caching their content at strategically placed physical nodes across the world. Azure CDN can also accelerate dynamic content, which cannot be cached, by leveraging various network optimizations using CDN POPs. For example, route optimization to bypass Border Gateway Protocol (BGP). 
The benefits of using Azure CDN to deliver website assets include: Better performance and improved user experience for end-users, especially when using applications in which multiple round-trips are required to load content.
Large scaling to better handle instantaneous high loads, such as the start of a product launch event.
Distribution of user requests and serving of content directly from edge servers so that less traffic is sent to the origin server.
Please refer to the below video for your reference. 

https://www.coursera.org/lecture/azure-infrastructure/cdn-content-delivery-network-bplZU

Storage is very important in Azure. Without storage then Azure would not exist. There are several different aspects of storage that we need to understand. We look at each of these different concepts. Things like the storage account, replication, lift/shift and so much more. 
Azure Content Delivery Network (CDN) is a global CDN solution for delivering high-bandwidth content. With Azure CDN, you can cache static objects loaded from Azure Blob storage, a web application, or any publicly accessible web server,by using the closest point of presence (POP) server. 
A content delivery network (CDN) is a distributed network of servers that can efficiently deliver web content to users. CDNs store cached content on edge servers in point-of-presence (POP) locations that are close to end-users, to minimize latency. 
Azure Content Delivery Network (CDN) offers developers a global solution for rapidly delivering high-bandwidth content to users by caching their content at strategically placed physical nodes across the world. Azure CDN can also accelerate dynamic content, which cannot be cached, by leveraging various network optimizations using CDN POPs. For example, route optimization to bypass Border Gateway Protocol (BGP). 
The benefits of using Azure CDN to deliver website assets include: Better performance and improved user experience for end-users, especially when using applications in which multiple round-trips are required to load content.
Large scaling to better handle instantaneous high loads, such as the start of a product launch event.
Distribution of user requests and serving of content directly from edge servers so that less traffic is sent to the origin server.
Please refer to the below video for your reference. 
Since this is the right category for the service, all other options are incorrect. 

https://docs.microsoft.com/en-us/azure/cdn/cdn-overview
https://azure.microsoft.com/en-in/blog/enable-azure-cdn-directly-from-azure-cloud-services-portal-extension/