Which suffix refers to the laws of a subject?

The suffix that refers to the laws of a subject is "-logy." This suffix is derived from the Greek word "logia," meaning "study of" or "science." It is commonly used in terms that denote a field of study or a body of knowledge. For example, in "biology," it indicates the study of life, while in "geology," it refers to the study of the Earth.

In contrast, the other suffixes have distinct meanings. For instance, "-atics" often pertains to a particular discipline or method, but does not specifically imply a comprehensive study or set of laws. Similarly, "-pathy" refers to a type of treatment or condition related to diseases, and "-ism" typically denotes a belief system or practice rather than the systematic study of a subject. Therefore, "-logy" is the most suitable choice when it comes to referring to the laws or systematic study of a subject.