Answer is (C)
TCP-Connection Oriented,Highly reliable,Slower.
UDP-Connectionless,Unreliable,Faster than TCP.
A)HTTP communication usually takes place over TCP/IP connections. The default port is TCP 80, but other ports can be used.HTTP only presumes a reliable transport; any protocol that provides such guarantees can be used;
B)Telnet is a client-server protocol, based on a reliable connection oriented transport. Typically, this protocol is used to establish a connection to TCP port number 23.
D)SMTP is a mail transport protocol, and in mail every single packet is important. If you lose several packets in the middle of the message the recipient might not even receive the message and if they do they might be missing key information. This makes TCP more appropriate because it ensure that every packet is delivered.
C)DNS primarily uses the User Datagram Protocol (UDP) on port number 53 to serve requests. DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server. When the length of the answer exceeds 512 bytes, larger UDP packets are used. Otherwise, the query is sent again using the Transmission Control Protocol (TCP).