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.

Fact: sound can be used for communication by animals.
Sound is frequency.

Fact: detailed observation of celestial objects requires a telescope.
celestial object star.

Fact: Mating is generally preceded by courtship.

animal courtship.