In a connection establishment using three$-$way handshaking, the value of the sequence number of the first TCP data packet sent from client A to server B is $100.$ For a packet sent back from server B to client A$,$ the sequence number is $200$ and the rwnd is $400.$ For the ACK packet sent from client A to server B$,$ what is the sequence number for a packet?

Question $22$ options:

a random number

none of the given choices

$101$

$400$

$201$

$500$

$601$

$300$