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.

Input: Consider Input: Fact: microbial fuel cells convert chemical energy into electrical energy.

Output: electrical energy electrons.


Input: Consider Input: Fact: All chemical reactions require activation energy to get started.

Output: activation energy enzyme.


Input: Consider Input: Fact: Most ecosystems get energy from sunlight.


Output: ecosystem habitat.