A group of closely related organisms capable of interbreeding to produce the fertile offspring are known as members of a

1. Analyze the question The question asks for the taxonomic group made up of organisms that are closely related and can interbreed to produce fertile offspring.

2. Explain the concept Biological classification arranges organisms into groups from the largest to the smallest:

Kingdom → Phylum → Class → Order → Family → Genus → Species

The species is the basic unit of classification. The standard definition (the biological species concept) is a group of organisms that can interbreed freely in nature and produce fertile offspring.

3. Go through the options

• A. Kingdom is the largest group. It contains a huge variety of organisms, such as all animals or all plants, that cannot all interbreed.
• B. Class is a broad group, for example Mammalia. A dog and a human are both mammals but cannot interbreed.
• C. Family is a group of related genera, for example Felidae (cats). Lions and domestic cats belong to the same family but do not produce fertile offspring together.
• D. Species contains organisms that interbreed and produce fertile offspring. This fits the definition.

4. Answer The correct option is D. species.

5. Exam tip Why is the word "fertile" important? A horse and a donkey can mate and produce a mule, but the mule is sterile. That shows horses and donkeys are separate species. So remember: species = interbreed + fertile offspring.