Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions

The search of alternative resources of energy has resulted in different directions. Many communities are burning garbage and other biological waste products to produce electricity.

Experimental work is being done to make synthetic fuels from coal, or coal tars. But to date, that process has proved expensive. Some experts are trying to revive hydroelectric power which is derived from streams and rivers. Fifty years ago, hydroelectric power provided one third of the electricity used in the United States, but today it supplies only four percent. The oceans are another source of energy. Scientists are studying ways to change the energy of ocean currents, tides, and waves into electricity.

What are many communities doing to produce electricity?

• A. 
  burning garbage and other biological waste products.
• B. 
  changing waste products into power
• C. 
  searching for alternative resources
• D. 
  all are correct