What procedure allows direct visualization of internal structures using a fiber optic scope?

The correct answer is endoscopy, which refers to the general procedure that enables direct visualization of various internal structures using a fiber optic scope. This procedure can be adapted to examine different parts of the body, such as the digestive tract, respiratory system, and other internal organs.

While arthroscopy, laparoscopy, and colonoscopy are all specific types of endoscopy targeting particular areas, the term "endoscopy" encompasses a broader range of techniques. Arthroscopy is used specifically for viewing joints, laparoscopy for examining the abdominal cavity, and colonoscopy for inspecting the colon. Therefore, the most accurate term to describe the procedure that utilizes a fiber optic scope for internal visualization in a general sense is endoscopy.