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.

Fact: If a planet becomes too hot, then it cannot maintain a balanced ecosystem. 
Question: If a planet becomes too hot, then it cannot maintain what?
balanced ecosystem.

Fact: navigation requires knowing which way to go. 
Question: What requires knowing which way to go?
navigation.

Fact: the urethra carries urine from the bottom of the bladder to a sphincter for urination. 
Question: What carries urine from the bottom of the bladder to a sphincter?

Urethra.