What type of system does not transmit, receive, route, or exchange information outside of itself?

The correct choice is Platform Information Technology (PIT) because this type of system is fundamentally designed to operate independently without the need to interact with external systems for information transmission or routing. PIT encompasses systems that facilitate information processing within a self-contained environment, focusing on internal functionality rather than external communication.

In contrast, other types of systems, such as distributed systems, cloud computing systems, and client-server models, are inherently designed for interaction with multiple nodes, clients, or external resources. Distributed systems consist of multiple interconnected components that work together, and they explicitly require communication between those components. Cloud computing systems rely on the distribution of services and resources across the internet, necessitating communication with numerous external services. The client-server model operates on a framework where clients request resources or services from a central server, making communication essential to its function.

Thus, while PIT stands apart by not involving any external interaction, the other systems are based on principles of connectivity and information exchange with external entities.