Which of the following is a common feature of nonpathogenic bacteria?

Nonpathogenic bacteria are generally known for their beneficial roles in various ecosystems, including on human skin. They contribute to the natural balance of the skin's microbiome, helping to prevent the overgrowth of harmful pathogens by competing for resources. These helpful bacteria can aid in maintaining skin health, supporting barrier functions, and even contributing to the skin's defense mechanisms.

The other options do not accurately represent the characteristics of nonpathogenic bacteria. For instance, nonpathogenic bacteria do not cause illness; instead, they typically support health. They may not have a specific preference for oily skin, and they should not be avoided as they play an important role in promoting a healthy skin environment. Understanding these aspects is crucial for recognizing the importance of maintaining a balanced microbial ecosystem on the skin.