TCP$-2$ Lab: Q$04\mathrm{.}2$ TCP SYNACK $($b$).$ What is it in this TCP segment that identifies the segment as a SYNACK segment?

The second segment in a TCP connection $($from server to client$)$ is always a SYNACK segment, so this segment is recognized as a SYNACK segment even though there is no explicit marking in this segment to indicate it is a SYNACK segment.

The SYNACK bit is set to $1$ in the "Flag" field in the TCP header.

The SYN bit and the ACK bit are both set to $1$ in the "Flag" field in the TCP header.

The TCP options field in the TCP header contains the ASCII characters "SYNACK", indicating that this is a SYNACK segment