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

Ex Input:
What do you call an abnormal mass of cells that is dividing improperly?

Ex Output:
tumor

Ex Input:
What process is involved in the formation of a waterfall, when a stream flows from an area of harder to softer rock?

Ex Output:
erosion

Ex Input:
What are seeds plants that produce naked seeds in cones called?

Ex Output:
gymnosperms