主机甲向主机乙发送一个(SYN = 1, Seq = x)的TCP段，期望与主机乙建立TCP连接，若主机乙接受该连接请求，则主机乙向主机甲发送的正确的TCP段可能是（）。
A.SYN = 0, ACK = 0, Seq = y, Ack = x 1
B.SYN = 1, ACK = 1, Seq =y , Ack =x 1
C.SYN = 1, ACK = 1, Seq = x 1, Ack = y
D.SYN = 0, ACK = 0, Seq =x 1 , Ack = y
正确答案：SYN = 1, ACK = 1, Seq =y , Ack =x 1