Which of the following protocol pairs can be used to send and retrieve e-mails (in that order)?

Consider a long-lived $$TCP$$ session with an end-to-end bandwidth of $$1$$ $$Gbps$$ ($$ = {10^9}\,$$ bits-persecond). The session starts with a sequence number of $$1234.$$ The minimum time (in seconds, rounded to the closest integer) before this sequence number can be used again is _______.

Consider the following statements.

I. TCP connections are full duplex
II. TCP has no option for selective acknowledgment
III. TCP connections are message streams

Identify the correct order in which a server process must invoke the function calls accept, bind, listen, and recv according to UNIX socket APL