Exam FC0-U61 topic 1 question 148 discussion

C. Password lockout Explanation: Password lockout limits the number of incorrect login attempts before temporarily disabling or locking an account. This helps prevent brute-force attacks, where attackers try many password combinations. Other options: Input validation prevents malicious inputs but does not directly stop brute-force attacks. System updates are important for security but do not specifically address brute-force attacks. Login auditing helps monitor login attempts but does not actively block brute-force attempts.

I'm assuming they are talking about passwords brute force attacks so I'd say C then