design . structure and Knowledge of software program is essential in _______ .A. Black-box testingB. Integration testingC. White-box testingD. None of the above

To answer the question, we need to understand the concepts of black-box testing, integration testing, and white-box testing.

1. Black-box testing: This is a testing technique where the internal structure and design of the software program are not known to the tester. The focus is on testing the functionality and behavior of the software from an end-user perspective. Therefore, knowledge of the software program's design and structure is not essential in black-box testing.

2. Integration testing: This type of testing is performed to verify the interaction between different components or modules of a software program. It ensures that the integrated system functions correctly as a whole. While knowledge of the software program's design and structure can be helpful in understanding the integration points, it is not essential for performing integration testing.

3. White-box testing: This testing technique involves examining the internal structure and design of the software program. Testers have access to the source code and use this knowledge to design test cases that target specific paths or conditions within the code. In white-box testing, knowledge of the software program's design and structure is essential.

Based on the above explanations, the correct answer to the question is C. White-box testing.