In this task, you need to write a topic word from the given fact. The topic word must have at least one word overlap with the given fact. The topic word often involves adding a new word from a related concept. In your topic word, use at least one word from the given fact. Topic words with two or more words work best.

Example Input: Fact: Playing is just one of many ways that mammals and other animals learn how to behave.
Example Output: animal kitten.

Example Input: Fact: Fungi have special structures for penetrating a host.
Example Output: animals can be hosts for fungi.

Example Input: Fact: Bivalves feed on plankton and nonliving organic matter.
Example Output:
Bivalve.