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: Most animals without backbones have a nervous system. 
Question: Which type of system do most animals without backbones have?

Answer: Nervous system.


Question: Fact: breathing is when fish convert from oxygen in water to oxygen in blood. 
Question: When fish convert oxygen in water to oxygen in blood this is called?

Answer: breathing.


Question: Fact: Sand and dust are formed by mechanical weathering. 
Question: What is a beach formed by?

Answer:
mechanical weathering.