Diseases are caused by biological agents called what?

Diseases are primarily caused by biological agents known as pathogens. Pathogens include a wide range of organisms that can cause disease in humans, animals, and plants, such as bacteria, viruses, fungi, and protozoa. Understanding the role of pathogens is crucial in fields like agriculture and public health, as they are the agents responsible for many infectious diseases and can have significant impacts on crop yields and human health.

While other terms in the options also refer to organisms that may cause some form of harm or disease, they do not encompass the broad definition of agents responsible for disease causation as directly as "pathogens." For instance, parasites specifically refer to organisms that live on or in a host and may cause harm, but they represent just one category of pathogens. Similarly, "microbes" is a general term that includes a wide variety of microorganisms, many of which are harmless or beneficial rather than disease-causing. The term "infectants" is less commonly used in scientific terminology and is not as widely recognized in the context of disease causation compared to pathogens. Therefore, calling diseases caused by biological agents "pathogens" accurately reflects the broad spectrum of organisms involved in disease processes.