instruction:
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: heating salt water leaves the salt on the surface. 
Question: heating salt water leaves the salt where?
answer:
on the surface.


question:
Fact: nerve receptors in the skin sense temperature and pain. 
Question: what in the skin sense temperature and pain?
answer:
nerve receptors.


question:
Fact: Something caused by malnutrition occurs when the immune system is not working properly. 
Question: What can cause the immune system to not work properly?
answer:

Malnutrition.