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: In the puberty stage is a time of significant mental, emotional and social change. 
Question: What is a time of significant mental and emotional change?
puberty.

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

Fact: most cephalopods have shells. 
Question: What have shells?

most cephalopods.