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: Oxygen is essential for cellular respiration for all aerobic organisms.
Example Output: aerobic organism.

Example Input: Fact: the emission of sulfur dioxide causes acid rain.
Example Output: acid rain causes.

Example Input: Fact: having no natural predators increases population size.
Example Output:
increase population more offspring.