Final answer:
The most appropriate measure for preventing unauthorized access to sensitive data in active memory is to encrypt the sensitive data. This ensures that even if access is obtained, the data would be unusable without decryption keys. Other security measures like two-factor authentication, updating antivirus software, and monitoring network traffic are also important but do not directly protect active memory data.
Step-by-step explanation:
In response to the question about the most appropriate measure to implement for a systems administrator receiving an alert for potential unauthorized access to sensitive data, several measures can be considered. Among these, encrypting sensitive data would be highly effective in protecting data in the event of unauthorized access, as encrypted data would still be unreadable without the proper decryption keys. This safeguard makes it harder for attackers to misuse the data even if they manage to access it in active memory.
Two-factor authentication is another important security measure that helps to ensure only authorized users can access certain systems, but it may not directly address data that is in active memory. Updating antivirus software can protect against malware that may lead to data breaches while monitoring network traffic can help detect and prevent unauthorized access attempts. However, encryption specifically targets the protection of the data itself.
Ultimately, while all these measures can form part of a robust security strategy, if the question is focused on protecting data in active memory, encryption stands out as the most directly relevant measure to implement.