Answer:
Genus
Step-by-step explanation:
Genus is a group of related plant or animal species. These group of species share a common evolutionary history which means that they are descended from a recent or distant common ancestor. These group of plant or animal species can not interbreed among themselves as the individuals of the different species can not interbreed to give rise to the fertile progeny.
Example: Solanum is a plant genus that includes many species such as nigrum, tuberosum, etc. The plants of S. nigrum and S. tuberosum can not interbreed in nature as they belong to different species.