Which of the Following Is Not an Advantage of Client/server

Which of the following is not an advantage of client/server computing over centralized mainframe computing?

A) It is easy to expand capacity by adding servers and clients.
B) Each client added to the network increases the network's overall capacity and transmission speeds.
C) Client/server networks are less vulnerable, in part because the processing load is balanced over many powerful smaller computers rather than concentrated in a single huge computer.
D) There is less risk that a system will completely malfunction because backup or mirror servers can pick up the slack if one server goes down.