$3\mathrm{.}08-2$ TCP sequence and ACK numbers $($b$).$ Consider the figure below, where a TCP sender sends $8$ TCP segments at t $=1,2,3,4,5,6,7,8.$ Suppose the initial value of the sequence number is $0$ and every segment sent to the receiver each contains $100$ bytes. The delay between the sender and receiver is $5$ time units, and so the first segment arrives at the receiver at t $=6.$ The ACKs sent by the receiver at t $=6,7,8,10,11,12$ are shown. The TCP segments $($if any$)$ sent by the sender at t $=11,13,15,16,17,18$ are not shown.

The segment sent at t$=4$ is lost, as is the ACK segment sent at t$=7.$

What is the ACK value carried in the receiver$-$to$-$sender ACK sent at t $=6?$

Group of answer choices

$1$

$0$

$100$

$200$

None of these other answers.

$2$