Which of the following best differentiates IaaS (Infrastructure as a Service) from PaaS (Platform as a Service)? 

IaaS and PaaS are two distinct models of cloud service delivery. IaaS provides fundamental computing resources such as virtual machines, storage, and networks, allowing users to run any operating system or application of their choice on the cloud infrastructure. Users have significant control over their infrastructure and are responsible for managing everything from the OS to applications. On the other hand, PaaS offers a managed platform for developers, providing tools and services to build, deploy, and manage applications without the complexity of underlying infrastructure management. PaaS typically includes development frameworks, database management, and middleware, making it easier for developers to focus on writing code rather than managing hardware or software stacks. Option A is incorrect as it reverses the roles of IaaS and PaaS. Option C is misleading because cost can vary significantly based on usage and service level, not just the type of service model. Option D is wrong; both IaaS and PaaS can be used for various scales of applications, from personal projects to enterprise-level systems. Option E is misleading as IaaS requires more management, but the extent of management can vary based on the specific PaaS solution.