How is "species" best defined?

The definition of "species" is best captured by identifying a group of potentially interbreeding organisms that can produce fertile offspring. This concept stems from the biological species concept, which emphasizes reproductive isolation as a key aspect of defining a species. Essentially, members of a species share genetic similarities and can interbreed under natural conditions, leading to the generation of viable offspring. This is crucial for maintaining the evolutionary integrity of the group.

In contrast, the other definitions portrayed in the options lack the necessary specificity and biological relevance. For instance, defining a species as a group of organisms with no common characteristics fails to acknowledge the shared traits that enable recognition and classification as a cohesive group. Similarly, a category that includes all living things is too broad and does not appropriately encompass the specific interactions and reproductive compatibility that define species. Lastly, describing a species as a random collection of different organisms disregards the structured nature of biological classification and the essential criteria needed to determine species boundaries. Therefore, the focus on reproductive capabilities and shared genetic traits makes identifying species in terms of their ability to interbreed the most accurate and scientifically supported definition.