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: ears made of cartilage. 
Question: What are ears made of?

Answer: cartilage.


Question: Fact: the amount of precipitation depends on condensation. 
Question: What does precipitation depend on?

Answer: condensation.


Question: Fact: weathering of rocks is caused by water. 
Question: What causes rocks to weather?

Answer:
water.