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.

[Q]: Fact: propulsion is used for flying by a spacecraft.
[A]: propulsion spacecraft.


[Q]: Fact: folding an object causes that object to change shape.
[A]: folding an object.


[Q]: Fact: an egg requires warmth to survive.
[A]:
egg sex cell.