A company has an Exchange Server environment. The company plans to migrate to the cloud. You need to recommend a cloud model that meets the following requirements: - Upgrade the existing email environ

PaaS provides a platform for developers to build and deploy applications but still requires the customer to manage their applications and data, not a ready-to-use email service.

Windows as a Service (WaaS) is a delivery model for Windows OS updates and lifecycle management, not a cloud service model for hosting or migrating email environments.

SaaS delivers fully managed applications over the internet, meaning the provider handles all server maintenance, patching, and upgrades automatically. For an Exchange Server migration, Microsoft 365 (Exchange Online) is a SaaS solution that upgrades the email environment while eliminating the need for the customer to manage any underlying infrastructure or application updates.

IaaS provides virtualized compute, storage, and networking resources but still requires the customer to install, configure, and maintain the operating system, Exchange Server application, and patches, which does not minimize maintenance.