Final answer:
An Upstream cable modem is used for upstream traffic only and converts data from DOCSIS to Internet protocols. Modem routers, Downstream cable modems, and Hybrid cable modems have different functionalities, but the correct answer to the student's question is an Upstream cable modem (B).
Step-by-step explanation:
A cable modem configured for upstream traffic that converts data from DOCSIS (Data Over Cable Service Interface Specification) to Internet protocols is known as an Upstream cable modem. This device specializes in sending data from a user's home network to the Internet, usually via a coaxial cable that connects to an Internet Service Provider (ISP). This conversion is necessary because DOCSIS is a telecommunications standard used by cable modems for data transfer over cable television systems, which is different from the standard Internet protocols such as TCP/IP.
Modem routers, on the other hand, typically handle both upstream and downstream traffic and can connect multiple devices to the Internet. Downstream cable modems focus on receiving data from the internet to the user, while Hybrid cable modems are capable of handling both upstream and downstream traffic.