Which of the following allows an internal application to be hosted without managing the underlying...

Platform as a Service (PaaS) is designed to host and run applications while the cloud provider manages the underlying infrastructure and operating system. With PaaS, an organization deploys its internal application code (and often configures runtime settings), but does not handle OS installation, patching, hardening, or most server maintenance tasks. This aligns with CompTIA A+ Core 1 cloud concepts that compare service models by responsibility: as you move from IaaS to PaaS to SaaS, the provider manages more of the stack.

IaaS (Infrastructure as a Service) provides virtualized compute, storage, and networking, but the customer still manages the OS, updates, drivers, and the application stack—so it does not meet the “without managing the underlying OS” requirement. SaaS (Software as a Service) delivers a complete finished application to users (like email or CRM), which typically doesn’t fit hosting a custom internal application you develop. UCaaS focuses on communication services (voice, video, messaging) rather than general application hosting. Therefore, PaaS is the best option for hosting an internal application without managing the underlying OS.