A data flow cannot go directly back to the same process it leaves. There must be at least other process(es) that handle(s) the data flow, produce(s) some other data flow, and return(s) the original data flow to the beginning process.
a) One
b) Four
c) Two
d) Three

Answer is A. One.

Refer below.

Explanation:

A data flow cannot go directly back to the same process it leaves. There must be at least one other process that handle(s) the data flow, produce(s) some other data flow, and return(s) the original data flow to the beginning process.

given the options, i would say your best bet is c. the modem supports up to 56 kbps, which is too low for video streaming. dial up modems use actual phone lines, which only can go up to 56 kbps as that's more than sufficient for traditional phone calls. this is also the reason why when a dial-up modem connects, you hear all those sounds. it's literally using the phone line to establish a connection.