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.

[EX Q]: Fact: harming an animal species has a negative impact on the population size of that species.
[EX A]: animal dog.

[EX Q]: Fact: the gravitational pull of the Moon on Earth 's oceans causes the tides.
[EX A]: earth ocean.

[EX Q]: Fact: Mutation creates new genetic variation in a gene pool.
[EX A]:
gene pool.