Answer:
21. B. Hydrologic Cycle
•water cycle also known as the hydrologic cycle, describes the continuous movement of water as it makes a circuit from the oceans to the atmosphere to the Earth and on again.
22. D. All of the above
•A renewable resource is a natural resource which will replenish to replace the portion depleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of time in a human time scale.
23. D. Crude oil
•oil may not be defined as a nonrenewable resource forever. That's because, in 2013, engineers came up with a chemical process that turns a water-and-algae mixture into crude oil. After refining, the oil could be used for gasoline and diesel or aviation fuels.
24. A. Carbon Cycle
•The burning of fossil fuels has the greatest and most direct impact on the carbon cycle.
