instruction:
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.
question:
Fact: an automobile engine transforms chemical energy into mechanical energy.
answer:
automobile engine.


question:
Fact: a human requires sleep to be healthy.
answer:
brainwaves during sleep.


question:
Fact: gases released during the use of fossil fuels causes global warming.
answer:

Fossil fuels.