. B. Computer systems sharing a common communication medium for the purpose of sharing information or devices is what a network is all about. The entities are usually workstations, and the medium is either a cable segment or a wireless medium such as an infrared signal.
A, C, and D are incorrect because a network, by definition, is two or more computers connected to share information. These three choices do not allow two or more PCs to share information; they are only setups of several connected devices or a PC connected to a peripheral device.