Which of the following is a distinguishing characteristic of facultative anaerobes?

Facultative anaerobes are unique because they have the ability to switch between aerobic respiration and fermentation based on the availability of oxygen. When oxygen is present, they will typically use aerobic respiration because it is more efficient in terms of energy yield. However, in environments where oxygen is limited or absent, they can switch to fermentation to continue generating energy. This versatility is a distinguishing characteristic of facultative anaerobes, allowing them to survive in a variety of environments.

The other answer choices do not accurately describe facultative anaerobes. They do not exclusively undergo aerobic respiration, nor do they prefer to grow without oxygen, as they can thrive in both aerobic and anaerobic conditions. Additionally, while they may require nitrogen for various cellular processes, it is not a defining trait for their classification as facultative anaerobes.