Write a correct answer to the given question based on its associated fact. Make sure that your answer is contained in the associated fact. Don't be creative and introduce any new word that is not mentioned in the associated fact! Remember that the associated fact has been rearranged to form the question. So, the correct answer words must lie within the associated fact. The correct answer can be a word, phrase, or even a sentence.
--------
Question: Fact: waves can be used to produce electricity. 
Question: What can be used to produce electricity?

Answer: waves.


Question: Fact: cross-pollination increases biodiversity. 
Question: What increases biodiversity?

Answer: cross-pollination.


Question: Fact: a rubber band snapping causes heat. 
Question: What does a rubber band snapping cause?

Answer:
heat.