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: Viruses cannot reproduce by themselves.
Viruses reproduce.

Fact: operating an automobile usually requires fossil fuels.
automobile car.

Fact: Vertebrates are animals that have a backbone.

backbone muscles move.