The options are: A) 2135 B) 503 C) 816 D) 1319

Consider the figure below in which a TCP sender and receiver communicate over a connection. The TCP sender sends an initial window of 3 segments. Suppose the initial value of the sender->receiver sequence number is 503 and the first 3 segments each contains 816 bytes. The delay between the sender and receiver is 7 time units, and so the first segment should arrive at the receiver at t=8. As shown in the figure below, the first segment is lost. What is the ACK number that the receiver sends in response at t=10