A scale model that proves the initial concept is called a

Domain model.

Explanation:

A domain model is a type of conceptual model used to show the structural elements and their conceptual constraints within a domain of interest. A domain model will include the various entities, their attributes and relationships, plus the constraints governing the conceptual integrity of the structural model elements comprising that problem domain.

there is no (:

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.