What characteristic is common to all pathogenic organisms?

The characteristic that is common to all pathogenic organisms is that they can cause disease. Pathogenic organisms are defined by their ability to invade host tissues and disrupt normal biological functions, leading to illness. This includes a wide range of microorganisms, such as bacteria, viruses, fungi, and parasites.

Pathogens can enter the body through various routes and invoke immune responses, which can result in symptoms ranging from mild to severe. Understanding this fundamental aspect helps in identifying and controlling infections, as well as in implementing effective treatment strategies.

The other options do not accurately reflect the nature of pathogenic organisms. For example, some pathogens are indeed harmful, but not all organisms considered pathogenic exist solely in water or are categorized strictly as bacteria. Pathogenicity encompasses a variety of microorganisms with diverse habitats and characteristics, making the ability to cause disease the defining trait.