Which environment would a security code reviewer set up to safely analyze third-party libraries and code without risking the main systems?

Setting up a sandbox environment is the most suitable choice for a security code reviewer to analyze third-party libraries and code without endangering the main systems. A sandbox is an isolated environment specifically designed to run untested or untrusted code securely. It allows for the execution of code in a controlled setting where any potential security issues can be identified and addressed without affecting the primary systems or production environments.

In a sandbox, resources and systems are separated from the main operating environment, enabling developers and security analysts to perform extensive testing and experimentation without the risk of introducing vulnerabilities or compromising sensitive information. This isolation is crucial when evaluating third-party libraries, which may contain malicious code or undiscovered vulnerabilities.

In contrast, QA and development environments are typically used for testing and building applications but may not provide the same level of isolation required to analyze potentially harmful code safely. Production environments, on the other hand, are critical for live applications and should always be protected against unverified code, as any vulnerabilities in this environment can directly impact users and organizational operations.

Therefore, the sandbox is the optimal choice for safely conducting code reviews of third-party libraries.