Which type of organisms are known to perform useful functions without causing harm?

Nonpathogenic organisms are those that do not cause disease or harm to their host. Instead, they can actually provide beneficial functions in various contexts. For example, certain nonpathogenic bacteria can help with digestion, enhance nutrient absorption, and even contribute to the protection against harmful pathogens by outcompeting them for resources.

In the realm of cosmetology, understanding nonpathogenic organisms is crucial as they can play a role in maintaining healthy skin and hair. Nonpathogenic organisms are often involved in processes such as fermentation, which can be beneficial in products related to skincare and haircare.

The other options refer to organisms that are associated with harm or negative effects. Pathogenic organisms are specifically known to cause diseases, while dangerous microorganisms and infectious agents typically imply a risk to health. Recognizing the difference between these types of organisms is fundamental in the field, especially when ensuring safety and efficacy in cosmetology practices.