What defines a "pathogen"?

A pathogen is defined as a biological agent that causes disease or illness. This includes a variety of microorganisms such as bacteria, viruses, fungi, and parasites that can invade a host organism and disrupt normal biological functions, leading to the manifestation of disease. Understanding the role of pathogens is critical in the field of disease detectives, as identifying these agents is essential for diagnosing and treating infections effectively.

The other options pertain to aspects of health and illness management but do not accurately describe a pathogen. For example, substances that promote health and well-being or compounds used to treat diseases are considered beneficial, whereas a pathogen is associated with harmful effects. Similarly, processes that help prevent illness do not define a pathogen; instead, they represent preventive measures against the diseases that pathogens cause. Thus, recognizing pathogens as agents of disease helps frame the broader context of public health and medical research for prevention and treatment strategies.