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.

Example Input: Fact: if graptolites are found in a place then that place used to be covered by water. 
Question: what are found in place to indicate a place used to be covered by water?
Example Output: graptolites.

Example Input: Fact: individual nerve cells transmit nerve impulses to other cells. 
Question: What transmit nerve impulses to other cells?
Example Output: individual nerve cells.

Example Input: Fact: Immunodeficiency occurs when the immune system is broken down. 
Question: Immunodeficiency occurs when the immune system is what?
Example Output:
broken down.