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

[EX Q]: Passage: There are multiple ways to prevent these situations from occurring. The three most common protective devices are fuses, circuit breakers, and surge protectors. Answer: fuses, circuit breaks & surge protectors
[EX A]: What are the three most common protective devices?

[EX Q]: Passage: The law of conservation of mass states that matter cannot be created or destroyed. Answer: destroyed
[EX A]: The law of conservation mass states that matter cannot be created or what?

[EX Q]: Passage: Body waves travel through the Earth and arrive at seismograms before surface waves. Answer: surface waves
[EX A]:
Body waves travel through the earth and arrive at seismograms before what?