CompTIA Network+

Answer: B - The Network Layer of the OSI model is responsible for connectionless data transfer and host addressing.

Key takeaway: The Network layer is responsible for the delivery of data and because it is connectionless, the Network layer is focused on expedient delivery of data as opposed to guarantee of data delivery. The guarantee aspect comes from Layer 4, the Transport layer, where the connection oriented protocols like TCP reside. The Network layer is also where host addressing takes place. Here hosts are addressed with IP addresses. These IP addresses are what the Network layer will use for routing and data delivery. Routers are the devices that can be found on this layer.