Account lockout policy would be the best mitigation technique in this scenario. It disables a user account after a certain number of failed login attempts, which can prevent the attacker from successfully leveraging the list of passwords to gain unauthorized access. Credential replay relies on repeated attempts, and an account lockout policy hampers this attack method by blocking the account after several unsuccessful tries. While network monitoring, conducting a security awareness training, and implementing two-factor authentication are all valid security measures, they would not specifically prevent the abuse of credentials through repeated login attempts by themselves. Patching would not help in this case as it is typically related to fixing software vulnerabilities, not addressing login attempt concerns.