Which suffix is associated with the term for a recording instrument?

The suffix that indicates a recording instrument is "-graph." In medical terminology, "-graph" is derived from the Greek word "grapho," meaning "to write" or "to record." Thus, when it is attached to a root word, it signifies an instrument used to create a record or a written account of a specific physiological or anatomical phenomenon. For instance, in terms like "radiograph" (an image produced on a photosensitive surface by radiation), the suffix "-graph" clearly denotes that something is being recorded.

The other suffixes relate to different types of instruments or concepts. "-scope" refers to an instrument used for viewing or examining, such as in "microscope," which allows one to see small objects. "-meter," which is used in terms like "thermometer," typically represents an instrument for measuring specific quantitative values. "-logy" denotes the study of a particular subject, as seen in "biology," referring to the study of life. Thus, the context of the question specifically points to the recording aspect, making "-graph" the appropriate choice.