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: riding a bike does not cause pollution.
bicycle pollution.

Fact: Skin color is a polygenic trait.
Skin color.

Fact: Viruses are not cells at all, so they are neither prokaryotes nor eukaryotes.

Viruses.