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: Smog contains particulates.
Example Output: particulates air.

Example Input: Fact: Vesicle transport requires energy, so it is also a form of active transport.
Example Output: Vesicle transport.

Example Input: Fact: Ants communicate with chemicals called pheromones.
Example Output:
ant insect.