The correct option is D Interbreeding
Species is the fundamental basic unit of classification. John Ray, an English naturalist coined the term species. A species is a biological unit. They possess distinct morphological characters. They interbreed among themselves to produce a fertile offspring. They are reproductively isolated from other species. They have a common gene pool. There is a free flow of genes among themselves and each species has the capacity to give rise to new species. In taxonomy, the determination of species is based on other characters but not interbreeding. The taxonomic species is distinguished on the basis of morphological characters, biochemical resemblances and anatomical characters.