*Question*
Q: How thick is the earth's continental crust, on average? Choices: - 60 kilometers - 15 kilometers - 25 kilometers - 35 kilometers A:
**Answer**
35 kilometers

*Question*
Q: In vertebrates, ovipary, ovovivipary, and vivipary are different strategies for what vital process? Choices: - respiration - absorption - circulation - reproduction A:
**Answer**
reproduction

*Question*
Q: Catalytic converters used on motor vehicles break down pollutants in what, yielding non-toxic compounds? Choices: - muffler - intake - oil - exhaust A:
**Answer**
exhaust

*Question*
Q: What do ranchers fear will happen if wolves return? Choices: - loss of environment - human predation - vegetation predation - livestock predation A:
**Answer**
livestock predation