Which of the following is vulnerable to a dictionary-based, password-cracking attack against wireless networks using WPA and pre-shared keys?

SSH public/private key authentication relies on asymmetric cryptography; there is no shared secret or password hash exposed to a dictionary attack.

WPA2-PSK uses the passphrase in a PBKDF2-based key derivation (CCMP/TKIP), and an attacker who captures the 4-way handshake can perform an offline dictionary attack by hashing candidate words and comparing them to the captured material. The PSK 'squirrelled' is a real English word present in standard wordlists, making it trivially crackable with tools like Hashcat or Aircrack-ng.

WPA2-Enterprise uses 802.1X with EAP and does not use a PSK at all, so the premise is contradictory and the complex string 'O3N7Ydp' would not be a dictionary word regardless.

EAP-MD5 uses a challenge-response mechanism over the wire and is vulnerable to different attacks (e.g., offline MD5 cracking of the challenge-response), not a straightforward WPA PSK dictionary attack.