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.

Example Input: Fact: magnetism can cause objects to repel each other.
Example Output: electricity causes magnet fields.

Example Input: Fact: Placental mammals are therian mammals in which a placenta develops during pregnancy.
Example Output: human placental.

Example Input: Fact: Fractures heal when osteoclasts form new bone.
Example Output:
bone is made of calcium.