Answer : B
a. Data link layer ii. Node to node delivery
b. Network layer iv. Routing
c. Transport later i. Flow control
d. Application layer iii. Mail services
Application Layer : It consists of protocols that focus on process-to-process communication across an IP network and provides a firm communication interface and end-user services
Transport Layer : The protocols of the layer provide host-to-host communication services for applications.
Network Layer : The network layer is responsible for packet forwarding including routing through intermediate routers, since it knows the address of neighboring network nodes
Data Link Layer : This layer is the protocol layer that transfers data between adjacent network nodes in a wide area network (WAN) or between nodes on the same local area network (LAN) segment.