Answer : C
a. UDP iv. Connectionless Transport Protocol
b. OSPF iii. Interior Gateway Routing Protocol
c. SMTP i. Message Transfer Protocol
d. HDLC ii. Bit-oriented Protocol
UDP : An unreliable connection less protocol used to control the management of application level services between computers. It is used for transport by some applications which must provide their own reliability.It works at Transport Layer.
OSPF : Open Shortest Path First dynamic routing protocol. A link state protocol rather than a distance vector protocol. It tests the status of its link to each of its neighbors and sends the acquired information to them.It works at Application Layer.
SMTP : Simple Mail Transfer Protocol is used to transport mail. Simple Mail Transport Protocol is used on the internet, it is not a transport layer protocol but is an application layer protocol.
IGP : Interior Gateway Protocol. The name used to describe the fact that each system on the internet can choose its own routing protocol. RIP and OSPF are interior gateway protocols.
HDLC : High-Level Data Link Control (HDLC) is a bit-oriented code-transparent synchronous data link layer protocol