What does the PSH flag tell the receiving application, and how does it differ from a normal ACK segment?

• A.PSH (Push) tells the receiving TCP stack to pass the data to the application immediately rather than buffering it. Without PSH, the OS might wait for the buffer to fill before delivering to the application. ACK alone (no PSH) typically indicates an acknowledgment segment without urgent data delivery pressure; PSH+ACK is used when the sender wants to ensure the application gets the current data without delay.
• B.PSH causes the sender to retransmit all previously unacknowledged segments immediately.
• C.PSH flags a segment as higher-priority than other segments, causing it to jump the queue at routers.
• D.PSH is equivalent to the TCP URG flag and routes data through the urgent pointer mechanism.