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: Amphibians have a relatively complex circulatory system with a three-chambered heart.
amphibian frog.

Fact: nerves can be used to feel heat and pressure on the skin.
epidermis.

Fact: Steroid hormones are made of lipids, such as phospholipids and cholesterol.

fats lipids.