Which of the following statements is true? (a)the total amount of water in an ecosystem is always increasing. (b)thermal pollution is the main disadvantage of hydroelectric power. (c)wood and water are nonrenewable natural resources. (d)the greenhouse effect is primarily caused by cars and trucks.

Astudent conducts an experiment to see how music affects plant growth. the student obtains four identical plants. each one is potted in the same type of soil and receives the same amount of sunlight and water each day. plant a listens to classical music for three hours each day. plant b listens to rock music for three hours each day. plant c listens to country music for three hours each day. plant d does not listen to any music at all. 2. based on the experiment in the scenario, which visual aid would be most in showing the change in the plants' heights over time? a. a pie chart b. a line graph c. a timeline d. a bar graph

What is an additional type of erosion found at the coast? what does it mean?

Mexico city is an example of how humans alter their environment because it was a. one of the world’s largest cities b. built on drained and filled lake beds c. built after conquest by the spanish d. once the capital of the aztec empire