Which suffix pertains to the study of?

The suffix that pertains to the study of is "-logy." This suffix is derived from the Greek word "logia," which means "study" or "science." It is commonly used in many scientific and medical terms to indicate a field of study or knowledge. For example, terms such as "biology" (study of life), "psychology" (study of the mind), and "neurology" (study of the nervous system) all utilize this suffix to specify the discipline being studied. This makes "-logy" the correct choice as it directly conveys the concept of study or examination within various contexts.