What is used to confirm that the actual output of your test code matches the expected output?

The correct choice highlights the use of the System.assert() method, which is specifically designed to validate that the actual output of test code aligns with the expected output. This method plays a crucial role in unit testing by allowing developers to set conditions that must be true. If the condition evaluates to false during the test execution, an assertion failure occurs, and the test fails, signaling a discrepancy between the expected and actual results.

In the context of software testing, maintaining accurate assertions is vital for ensuring the correctness of code changes. By using System.assert(), developers can create reliable tests that enforce expected behavior in their applications, enhancing code quality and facilitating easier debugging.

The other options, while related to debugging or checking code, do not serve to validate the output in the same manner as System.assert(). For instance, System.debug() is primarily used for logging purposes, allowing developers to see messages in the debug logs but not to confirm outputs. Similarly, System.verify() and System.check() do not exist as standard methods in the context of assertions and testing within the Salesforce platform, further reinforcing the uniqueness of System.assert() for this specific function.