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

Q: Passage: Cutting down on the use of chemical fertilizers is one way to prevent dead zones in bodies of water. Preserving wetlands is also important. Wetlands are habitats such as swamps, marshes, and bogs where the ground is soggy or covered with water much of the year. Wetlands slow down and filter runoff before it reaches bodies of water. Wetlands also provide breeding grounds for many different species of organisms. Answer: dead zones

A: Cutting down on the use of chemical fertilizers and preserving wetlands are ways to prevent what "unlivable" regions in bodies of water?
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Q: Passage: Graphs are very useful tools in science because they display data visually. Three commonly used types of graphs are bar graphs, circle graphs, and line graphs. Each type of graph is suitable for a different type of data. Answer: graphs

A: Bar, circle, and line are examples of what kind of data visualization?
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Q: Passage: Polarized filters block 50% of unpolarized light. If two filters are oriented so that their polarization axes are aligned, how much light is transmitted? What about if their axes are oriented perpendicular to each other? Draw two diagrams below to support your answers. Answer: 50%

A:
How much unpolarized light does a polarized filter block?
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