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: Flowing water can slowly dissolve carbon in sedimentary rock.
flowing water fall force.

Fact: Lung cancer is most often caused by exposure to tobacco smoke.
lung cancer also called.

Fact: plant reproduction often requires pollen.

bees carry pollen.