Which option is NOT an example of a contingency plan?

The correct choice identifies an action that does not align with the fundamental purpose of a contingency plan. Contingency plans are designed to ensure that an organization can continue its operations and quickly recover from unexpected events or disruptions. This typically involves preparing backup solutions, alternative pathways, and structured responses to crises.

In the context of the options provided, using backup power supplies, configuring routers for alternative routes, and implementing staff response plans all illustrate proactive measures put in place to manage emergencies or unforeseen circumstances effectively. Each of these options serves as a means of ensuring that critical functions can continue or be quickly restored when a significant disruption occurs.

On the other hand, installing switches in building closets is more of a standard operational practice involved in network infrastructure setup rather than a strategy aimed specifically at contingency planning. This action pertains to the setup and maintenance of the network's physical environment, which does not directly address recovery or response to emergencies. Thus, it does not fulfill the criteria of a contingency plan.