Answer the following question given this paragraph: 

There is great variation among species that make up the animal kingdom. Some of this variation is shown in Figure below . Despite the variation, there are a number of traits that are shared by all animals. The fact that all animals have certain traits in common shows that they share a common ancestor. How did such a diverse group of organisms evolve? What traits do all animals share? Read on to find out.


Q: The fact that all animals have certain traits in common shows that they share what?


A:
a common ancestor