Convergent evolution is the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. Common examples are microbats, toothed whales and shrews developed sonar-like echolocation systems used for orientation, obstacle avoidance and for locating prey. Several groups of ungulates have independently reduced or lost side digits on their feet, often leaving one or two digits for walkingSo, the correct answer is 'Convergent evolution'