An IT manager is concerned with the advancement of brute-force attacks.

The correct answer is C. Enforce multifactor authentication for all users . Brute-force attacks attempt to guess passwords or other hidden values by trying many possible combinations. The All-in-One Exam Guide describes brute force as a method in which an attacker guesses many or all possible values, most commonly to crack a password. Complex passwords help, but a sufficiently advanced brute-force attack can still target passwords through leaks, dictionaries, credential stuffing, or repeated guessing. Multifactor authentication is stronger because it requires an additional factor beyond the password, such as a token, authenticator app, SMS code, voice call, or biometric factor. The A+ objectives list multifactor authentication under logical security and also include related MFA methods such as hard tokens, soft tokens, SMS, voice call, and authenticator applications. Restricting logon hours and applying OS updates are useful security practices, but they do not directly address password-guessing attacks as effectively as MFA.