Why the client host send the number $1678$ to the client host as shown by the figure?

a$.$

to allow the client to know the previous actions done by this server on the client.

b$.$

to allow the server to know the size of the amazon file at the client.

c$.$

none of these objects.

d$.$

to allow the server to know the previous actions done by this client on the server.

e$.$

to allow the server to know the size of the ebay file at the client.