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: Tropical cyclones convert heat energy into mechanical energy. 
Question: What converts heat energy into mechanical energy?

Answer: tropical cyclones.


Question: Fact: Stimuli can cause the brain to experience pain. 
Question: What can cause the brain to experience pain?

Answer: stimuli.


Question: Fact: decreased light intensity can cause cell walls to relax. 
Question: What can cause cell walls to relax?

Answer:
Decreased light intensity.