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.

Input: Consider Input: Fact: An animal requires oxygen for survival. 
Question: What does an animal need for survival?

Output: Oxygen.


Input: Consider Input: Fact: Hummingbirds co-evolved with plants. 
Question: Hummingbirds are what they are today as a necessary consequence of their relationship to what?

Output: Plants.


Input: Consider Input: Fact: nutrients are required for growth throughout their lives. 
Question: What is required for growth through life?


Output: nutrients.