Tsunamis are caused by . a. underwater volcanoes
b. El Niño
c. underwater earthquakes
d. global warming

Which of the following is a cost of urbanization? a-cities can provide a high standard of living. b-cities are hubs of entertainment and education. c-paving over land changes the environment. d-job opportunities are greater in urban centers.

Study the diagram of a cell. which structure is found only in plant cells and functions in the process of photosynthesis? w x y z

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere