What feature of a browser can be configured to act as a firewall?

The feature of a browser that can be configured to act as a firewall is the proxy settings. Proxy settings allow a browser to connect to the internet through an intermediary server. This server can filter and control the data that is sent and received, effectively acting as a barrier between the user's device and the internet. By routing traffic through a proxy, users can enhance their security through content filtering, anonymity, and monitoring of outgoing and incoming traffic, which contributes to a firewall-like function.

In contrast, cookie settings primarily manage how cookies are stored and accessed by websites, which do not facilitate firewall capabilities. JavaScript options are related to enabling or disabling JavaScript execution on websites and do not provide any network security features. Bookmark management deals with saving and organizing URLs for easy access and has no implications regarding data protection or network filtering.