What is the suffix used to indicate an instrument for viewing?

The suffix that indicates an instrument used for viewing is "-scope." This suffix comes from the Greek word "skopein," meaning "to look" or "to examine." Instruments that end with "-scope" are specifically designed to allow visualization of the interior of a body cavity or structure. For instance, a "microscope" is used to view small entities such as cells, while an "endoscope" is utilized for examining the interior of a hollow organ.

In contrast, the other suffixes serve different purposes. The suffix "-tomy" refers to making an incision or cutting into a part of the body, typically associated with surgical procedures. "-itis" denotes inflammation and is commonly used in the naming of conditions resulting from inflammation, like arthritis or appendicitis. Lastly, "-plasty" indicates a surgical repair or reconstruction of a body part, as seen in terms like rhinoplasty (surgical reshaping of the nose). Thus, the choice of "-scope" is specifically tied to viewing and examination, making it the correct answer.