Which term describes a group of similar organisms that can breed and produce fertile offspring?

The term that describes a group of similar organisms capable of breeding and producing fertile offspring is "species." This concept is fundamental in biology as it helps define the criteria for classification of living organisms. The species concept emphasizes that members of a species share common characteristics and genetic makeup, allowing them to interbreed successfully under natural conditions.

When individuals from the same species mate, they typically produce offspring that can also reproduce, ensuring the continuation of their genetic lineage. This reproductive isolation helps maintain distinct boundaries between different species, preventing hybridization with other species, which often leads to offspring that may be sterile, such as mules (the hybrid of a horse and a donkey).

In contrast, the other terms play different roles in biological classification. "Family" is a higher taxonomic rank consisting of multiple genera (plural of genus), "genus" refers to a group of species that are closely related, and "population" describes a group of individuals of the same species living in the same area at a given time. Therefore, the correct answer highlighting the ability to breed and produce fertile offspring, which is central to the definition of a species, is indeed "species."