Which network technology addresses these customer business needs: shrinking budgets and IT staffs, more complex networks, and an increased need for network security?（）

A.A network that is restricted.to A single building ,A group of buildings, or even A single room.
B.A network that encompasses an entire city or metropolitanared and connects multiple LANs.
C.A network that connects client devices wirelessly using radio waves.
D.A network that crosses metropolitan, regional, or national boundaries.