Which authentication method requires clients to enter a passphrase to connect?

The chosen answer, which pertains to WPA/WPA2 PSK (Pre-Shared Key), is correct because this authentication method explicitly requires users to input a shared passphrase or key when connecting to a secured Wi-Fi network. By using a PSK, the network relies on a single, common passphrase that all allowed users must know, providing a measure of security against unauthorized access, as only those with the passphrase can connect.

In contrast, other options do not require a passphrase or use different mechanisms for authentication. For instance, WPA2 Enterprise typically employs a RADIUS server for user authentication, which utilizes usernames and passwords rather than a simple passphrase, making it suitable for enterprise environments where individual credentials are necessary. WEP (Wired Equivalent Privacy), while it can use a passphrase to derive a key, is outdated and considered insecure due to vulnerabilities in its encryption method. Open authentication allows users to connect to the network without any credentials, providing no security and making it the least secure option available.