Answer:
a; circuit-switched network.
b; No, it does not need congestion control.
Explanation:
For A;
A circuit-switched network is a better option for this application. This is because of the fact that the application is made up of long sessions with smooth data transfer capacity needs.
The transmission rate is known, and does not transmit in short intervals(short signals), every application session can have a bandwidth reserved without significant bandwidth wastage.
Also, the overhead expenses of setting up and tearing down connections are canceled out over the extensive period of running an application session.
For B;
If the packet-switched network is used, and traffic in the network comes from the said application. Even if every applications transmit one or more network connections. Still, we already know that every connection has enough transmission capacity to handle majority of the application data rates, no congestion(insignificant queuing) will happen.
This goes to say that no congestion control will be needed given such broad-based connection.