Given a scientific question, generate a correct answer to it.

Ex Input:
Who created the idea of an evolutionary tree to represent the relationships between different species and their common ancestors?

Ex Output:
charles darwin

Ex Input:
What is the smallest particle of an element that still has the properties of that element is called?

Ex Output:
atom

Ex Input:
The process of breaking down food into nutrients is known as __________

Ex Output:
digestion