Correct : b

Network layer (a): Responsible for packet routing between networks, determining the best path for data transmission from source to destination. This matches functionality (I) - Packet routing.

Transport layer (b): Provides host-to-host communication, ensuring end-to-end delivery of data between processes on different hosts. This matches functionality (III) - Host to host communication.

Data link layer (c): Handles framing of data into frames and provides error detection and correction mechanisms for reliable transmission over the physical medium. This matches functionality (II) - Framing and error handling.

Therefore, the correct matching is: Network layer with Packet routing, Transport layer with Host to host communication, and Data link layer with Framing and error handling.

✅ Final Answer: Option (B) — (a)-(I), (b)-(III), (c)-(II).

Reason: Each OSI layer has specific functions: Network layer routes packets, Transport layer provides host-to-host communication, and Data link layer handles framing and error control.