Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Most metalloids have some physical properties of metals and some physical properties of nonmetals. They fall between metals and nonmetals in their ability to conduct heat and electricity. They are shiny like metals but brittle like nonmetals. All exist as solids at room temperature. Answer: silicon
[EX A]: What is an example of a metaloid element?

[EX Q]: Passage: Hair, hair follicle, and oil glands. The oil, called sebum, helps to prevent water loss from the skin. The sebaceous gland secretes sebum, which waterproofs the skin and hair. Answer: sebum
[EX A]: What does the sebaceous gland secrete which waterproofs the skin and hair?

[EX Q]: Passage: Volcanoes may be active, dormant, or extinct. This depends on whether there is the possibility of magma in their magma chambers. Answer: magma
[EX A]:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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Volcanoes are termed active, dormant, or extinct depending on the possibility of the presence of what in chamber structures?

