Which of the following best describes the role of network segmentation?

The role of network segmentation is to enhance security by preventing unauthorized access to sensitive data through isolation. This is achieved by dividing a larger network into smaller, manageable segments or sub-networks. Each segment can be configured with its own security controls and policies, making it more difficult for an attacker to gain access to critical resources. If a breach occurs in one segment, the potential impact is limited, thus protecting the sensitive data housed in other segments.

The other options address aspects that are not primary functions of network segmentation. For instance, while reducing packet size can be beneficial for network performance, it is not related to segmentation. Similarly, network segmentation does not eliminate the need for firewalls; rather, it often works in conjunction with firewalls to provide a multi-layered security approach. Lastly, improving user experience on websites is more associated with network performance optimization rather than segmentation per se.