The correct answer is: A. checking
Checking is the process of verifying that the software meets the requirements specified in the software requirements specification (SRS). It is done by comparing the actual software to the SRS, and by performing tests to ensure that the software works as expected.
Checking can be done in both simulated and line environments. Simulated environments are used to test the software in a controlled environment, without the risk of impacting the production environment. Line environments are used to test the software in the actual production environment, to ensure that it works as expected in the real world.
Usability is the ease with which a user can use a product or system. It is a measure of how well the product or system meets the user’s needs and expectations.
Validity is the degree to which a test measures what it is supposed to measure. A valid test is one that measures the intended construct, and not something else.
Validation is the process of ensuring that a product or system meets the needs of the users. It is done by gathering feedback from users, and by making changes to the product or system based on that feedback.
None of the above options are correct.