Which of the following is a characteristic of living things?

The characteristic of living things that is most fundamental is their ability to use energy and have metabolism. Metabolism encompasses all the biochemical processes that occur within a living organism to maintain life, including transforming food into energy, synthesizing necessary compounds, and breaking down waste products. This process is essential for growth, reproduction, and maintaining homeostasis.

In contrast, the ability to fly and the ability to move independently are not universal traits among all living organisms. For instance, many living things, such as plants or certain microorganisms, do not have the capability to move voluntarily or fly, yet they are still classified as living due to their metabolic processes. Additionally, the idea of existing in isolation does not apply to most living organisms, which often interact with their environment and other organisms for survival. Thus, the use of energy and metabolism stands out as a defining characteristic common to all living organisms.