Which of the following statements about hydropower is true?

A. Dams have little or no impact on native aquatic organisms.
B. Hydropower includes dams, tides, and ocean currents.
C. Dams are relatively inexpensive to build but are expensive to operate.
D. The Wild and Scenic Rivers Act fosters the hydroelectric development of U. S. waterways.
E. Humans downstream of a dam may be exposed to waterborne diseases if the dam breaks.

Several processes form metal ore. match each process to its description. volcanic activity weathering hydrothermal energy rocks break down as they interact with air and water. arrowright density differences and other factors cause metals to concentrate in igneous rocks. arrowright seawater heats up from contact with hot rock, and metals dissolve in it. the water rises and contacts cooler water, causing metal ores to settle on the ocean floor. arrowright

Greg drew a diagram to compare two of the fundamental forces. which labels belong in the areas marked x, y and z? gravitational force electromagnetic force x. attractive y repulsive z: infinite range x: infinite range y attractive z. repulsive x. always attractive y: infinite range z: attractive or repulsive x. attractive or repulsive y infinite range z: always attractive

What component of earth’s atmosphere exists entirely as a result of photosynthesis?