What sequence of packets is sent during the initial TCP three-way handshake?

A.
SYN, URG, ACK

B.
FIN, FIN-ACK, ACK

C.
SYN, ACK, SYN-ACK

D.
SYN, SYN-ACK, ACK

Explanation:
This is referred to as a "three way handshake." The "SYN" flags are requests by the TCP stack at one end of a socket to synchronize themselves to the sequence numbering for this new sessions. The ACK flags acknowlege earlier packets in this session. Obviously only the initial packet has no ACK flag, since there are no previous packets to acknowlege. Only the second packet (the first response from a server to a client) has both the SYN and the ACK bits set.