Networks that connect computers together within a small geographical area are called LAN networks.
Networks that connect computers over the largest geographical area are called WAN networks.
The problem with this question is that there is no answer to "simplest network" in the list of networks. However, with the answers given, I would mark these:
LAN --> Simplest Network. Local Area Networks connect small amounts of computers on one network, such as your home network, and can be used in homes, hospitals, or offices.
MAN --> Small Region. Metropolitan Area Networks connect cities or towns together on one network.
WAN --> Largest Area. Wide Area Networks connect entire countries together. One example of a WAN is the internet.