Natural gas, coal and oil are all examples of which type of energy source?

What is the best known, and most significant human alteration of the carbon cycle?

Which of the following can we utilize as energy from the sun? 

Which of the following is a possible consequence of global warming? 

When you turn off the water between washing dishes, which conservation effort are you practicing? 

Wood is classified as a biomass fuel.

The original source of geothermal energy is the sun.

Economy is the way in which goods and services are made, sold, and used in a country.

Human activities cause global warming.

The Earth provides humans with an unlimited amount of fossil fuels, and they are considered renewable.