Which technique isolates and analyzes unknown files by executing them in a controlled environment to protect endpoints and data?

File sandboxing is the correct answer because it directly describes the process of executing unknown files in a secure, isolated environment to observe their behavior without risking the actual system. This technique is crucial for identifying malware, including zero-day threats. Crypto file ransomware protection using a file hash calculation is incorrect because hash calculations identify known malicious files, not unknown ones, and don't involve execution. File retrospection using continuous scan and analyses is a broader concept of continuously monitoring files for changes or new threat intelligence, but it doesn't specifically involve executing unknown files in isolation. Phishing file quarantine using an internal environment to store attached files is incorrect as it focuses on storing potentially malicious email attachments, not on executing and analyzing unknown files in a controlled, isolated environment.