What can testing demonstrate?

Testing primarily serves to reveal defects within software, making it a critical activity in the software development lifecycle. When testing is conducted, it involves executing the software under various conditions to identify any discrepancies between the expected outcomes and the actual results. This process highlights defects that exist, showcasing areas that require attention and improvement.

Option B is accurate because it acknowledges that testing can and often does uncover defects present in the system. While it might not uncover all defects or guarantee that the software is completely defect-free, it plays a pivotal role in illustrating where issues reside.

In contrast, other options present misconceptions. The assertion that testing can demonstrate no defects is problematic. Testing can enhance confidence that the software is functioning correctly, but it cannot unequivocally prove the absence of defects. Similarly, stating that testing can confirm the software's correctness overlooks the inherent limitations of testing; it can show that the software operates as expected within the tested scenarios, but it cannot verify correctness in all possible situations. Lastly, the idea of demonstrating no hidden defects is also misleading, as testing cannot guarantee that there are no undiscovered issues beyond what has been tested.

Thus, option B accurately encapsulates the purpose of testing in revealing defects within the software.