A captured TCP segment has both the FIN and ACK flags set. What is the most likely purpose of this segment within an established TCP session?

A segment with the FIN flag set signals that the sender has no more data to transmit and wishes to begin gracefully closing its side of the connection; the ACK flag alongside it simply acknowledges previously received data, as TCP nearly always keeps ACK set once a connection is established. A brand-new connection request would carry only SYN (option B), acknowledging the opening handshake would occur with SYN-ACK earlier in the exchange (option C), retransmission requests aren't signaled via a distinct flag combination in this way (option D), and keep-alive probes are a separate mechanism not indicated by FIN-ACK (option E).