Which term refers to a group of organisms that can interbreed and produce fertile offspring?

• A. Sex chromosome
• B. Species
• C. Mutation
• D. Transfer RNA

Answer: (B)

Under the Biological Species Concept, a species is a group of organisms that can interbreed and produce fertile offspring. This idea emphasizes reproductive compatibility and gene flow within the group, which helps maintain a distinct lineage over generations. The other terms refer to different concepts: a sex chromosome determines the sex of an organism, mutation is a change in DNA, and transfer RNA is a molecule involved in building proteins. The description given—a group that can produce fertile offspring—best matches species. (An example: hybrids like mules show why reproductive compatibility matters—when hybrids are sterile, it supports keeping those parent groups as separate species.)