According to the CISA - Certified Information Systems Auditor Study Guide1, the correct answer to your question is A. Encrypt the disk drive. This is because encryption is a logical security measure that can protect data even if the physical device is stolen or lost. Encryption makes the data unreadable and inaccessible without the proper key or password. The other options are not as effective as encryption in this scenario.
Two-factor authentication is a user authentication method that requires two pieces of evidence to verify the user's identity, such as a password and a code sent to a phone. However, this does not prevent unauthorized access to the data if the laptop is already logged in or if the attacker can bypass the authentication. Enhancing physical security is a preventive measure that can reduce the risk of theft, but it does not guarantee that theft will not occur or that the data will be safe if it does. Requiring the use of cable locks is another preventive measure that can deter thieves, but it can also be easily cut or removed by a determined attacker.