Final answer:
Focusing on a distant object is not a method for checking the visual clarity of a rigid endoscope; instead, submersion in solution, brightness testing, and image quality testing are used.
Step-by-step explanation:
The method for checking the visual clarity of a rigid endoscope that is NOT correct is d) Focusing on a distant object. The visual inspection of an endoscope typically involves checking for image quality, which includes ensuring that the endoscope provides a clear and undistorted view of the object being examined. Methods such as submersion in solution are used to check for leaks that can compromise the endoscope's function, while brightness testing would be used to verify that the illumination system within the endoscope is working properly. All of these methods are crucial to maintaining the operational efficiency and safety of endoscopic equipment.