One drawback of a client-server network is:

A client-server network architecture can provide multiple benefits, such as centralized management of resources and data backups. However, one significant drawback is that it may become costly and complex. This complexity arises from several factors, including the need for specialized hardware, such as servers, which can be expensive to purchase and maintain. Additionally, setting up a client-server network often requires skilled IT personnel to manage the network, perform regular maintenance, and troubleshoot issues, which can further increase operational costs.

Furthermore, as the network grows, the demands on the server increase, potentially requiring additional investments in infrastructure and capacity to ensure reliable performance. This complexity can also lead to vulnerabilities if not managed correctly, as a well-designed client-server network involves a considerable amount of planning and ongoing management.

The other choices highlight advantages or characteristics rather than drawbacks. Simplicity in setup and centralized management for backups are indeed benefits of a client-server architecture, whereas resource sharing is a more general characteristic of networks. Therefore, recognizing the complexity and potential costs is essential in understanding the limitations of client-server networks.