Which of the following best describes anatomy?

The correct choice is indeed the study of body structures. Anatomy focuses specifically on the physical arrangement and relationships of the different components of the body, including organs, tissues, and cells. This foundational knowledge is crucial in fields like healthcare and beauty services, as it allows professionals to understand how to properly care for and treat the body in specific contexts, such as nail technology.

The other options represent different areas of biological study. The study of the body's functions relates to physiology, which explains how the various systems and organs work. Investigating disease mechanisms falls under pathology, where one examines what causes diseases and how they affect the body. Lastly, the study of biochemical processes pertains to biochemistry, focusing on the chemical substances and processes that occur within living organisms. Each of these fields provides essential information but does not directly align with the definition of anatomy itself.