The establishment of a TCP connection involves a negotiation called 3 way handshake. What type of message sends the client to the server in order to begin this negotiation?

RST (Reset) is used to abruptly terminate an existing connection or reject an invalid connection attempt, not to initiate one.

ACK (Acknowledgment) is the third step of the handshake sent by the client after receiving the server's SYN-ACK, not the first step.

SYN-ACK is the second step of the handshake, sent by the server in response to the client's initial SYN, not the opening message from the client.

The TCP three-way handshake begins when the client sends a SYN packet with a randomly generated Initial Sequence Number (ISN) to the server. The server responds with a SYN-ACK, and finally the client sends an ACK to complete the connection establishment. SYN is specifically the initiation message that signals the client's intent to open a connection.