What are pathogens?

Pathogens are defined as microorganisms that cause disease. This includes various types of bacteria, viruses, fungi, and parasites that can invade the body and disrupt normal physiological functions, leading to illness. Understanding pathogens is crucial in healthcare, as it guides the diagnosis, treatment, and prevention of infectious diseases.

The other options describe functions of different types of microorganisms but do not capture the essence of what a pathogen is. For instance, some microorganisms do aid in digestion, as seen in the case of beneficial gut bacteria. Others may help in preventing infection or enhancing immune responses, such as probiotics or certain immune-modulating microorganisms. However, the defining characteristic of pathogens is their ability to cause harm and lead to disease, making the correct choice focused on their pathogenicity.