Which of the following test case design techniques is white box (structure-based)?

White box testing techniques, also known as structure-based techniques, focus on the internal structure of the software. Decision testing (C) is a white box technique that involves creating test cases to execute specific decision points in the code, such as conditional statements. This ensures that all possible paths through the code are tested, helping to identify defects related to the control flow of the application. Other techniques listed, such as use case testing and state transition testing, are black box techniques that focus on the software's functionality from the user's perspective​​.