Answer: d) Network
Explanation: IPv4(internet protocol version 4) is the decimal-digit numeric value for the internet protocol.It helps in the identification of the hosts through logical addresses. The functioning of IPv4 helps in the routing of the information over the network.
The network layer contains router that is responsible for the routing of message between the nodes of the path.Router functions with internet protocol.Other options are incorrect because protocol is the set of riles,data link layer works for managing the movement of data and transport layer monitors the transmission of data.Thus ,correct option is option(d)