Which suffix represents the study or knowledge about a specific subject?

The suffix that represents the study or knowledge about a specific subject is -logy. This suffix is derived from the Greek word "logos," meaning "word" or "study." It is commonly used in terms such as "biology" (the study of life), "psychology" (the study of the mind), and "geology" (the study of the Earth). Each of these terms indicates a field of knowledge that focuses on a particular area of inquiry.

The other suffixes provided have different meanings. The suffix -ism refers to a practice or belief system, often used in terms like "buddhism" or "realism." The suffix -iatry denotes a field of medicine or healing, such as in "psychiatry" (the treatment of mental disorders). The suffix -esis generally indicates a condition or process, as seen in "hypothesis" or "diagnosis." Understanding these distinctions helps clarify the significance of -logy as the suffix specifically associated with the study of particular subjects.