What is the primary focus of Black Box Testing?

Black Box Testing is a software testing method where the tester evaluates the software's functionality without any knowledge of its internal code structure or implementation. The focus is on input and output, ensuring that the software behaves as expected according to the specified requirements. Test cases are designed based on the requirements and functionality of the application, allowing testers to validate if the system meets its intended purpose. This approach is beneficial for validating user requirements and ensuring that the software works correctly from the user's perspective. Option A (Internal code structure) is incorrect because Black Box Testing specifically ignores the internal workings of the software. Option B (User interface design) is not the primary focus, although UI elements may be tested within the broader context of functionality. Option D (Integration of system components) pertains more to integration testing, which examines how different modules interact. Option E (Performance metrics) is relevant to performance testing, not Black Box Testing, which assesses functional correctness.