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: fog is formed by water vapor condensing in the air.
fog is formed.

Fact: using renewable resources to generate power reduces greenhouse gases.
greenhouse gas carbon.

Fact: Nerve impulses are electrical in nature.

Nerve impulses are electrical in nature.