Infrastructure as a service (IaaS) is an instant computing infrastructure, provisioned and managed over the internet. The IaaS service provider manages the infrastructure, while you purchase, install, configure, and manage your own software Incorrect Answers:
A: Software as a service (SaaS) allows users to connect to and use cloud-based apps over the Internet. Common examples are email, calendaring, and office tools. In this scenario, you need to run your own apps, and therefore require an infrastructure.
B:
Platform as a service (PaaS) is a complete development and deployment environment in the cloud. PaaS includes infrastructure-servers, storage, and networking-but also middleware, development tools, business intelligence (BI) services, database management systems, and more. PaaS is designed to support the complete web application lifecycle: building, testing, deploying, managing, and updating.
Reference:
https://azure.microsoft.com/en-us/overview/what-is-iaas/
https://azure.microsoft.com/en-us/overview/what-is-saas/
https://azure.microsoft.com/en-us/overview/what-is-paas/