Which of the following best describes a method that utilizes internal knowledge of the code during application testing?

White-box testing refers to a testing method that involves an understanding of the internal workings of the application being tested. During this type of testing, the tester has access to the source code and is aware of the internal data structures, algorithms, and the control flow of the application. This knowledge allows testers to create test cases that can thoroughly evaluate the internal logic and processing of the software.

By using this method, issues such as logical errors, code complexity, and specific pathways through the code can be identified and fixed. White-box testing is particularly effective for unit testing, where individual components or functions of the software are tested in isolation. This contrasts with black-box testing, where the focus is on input and output without knowledge of the internal code structure, and gray-box testing, which combines elements of both black-box and white-box approaches. Functional testing, on the other hand, primarily focuses on validating that the software operates according to specified requirements without delving into its internal logic.