Which source would be most effective in answering the following research question: What is meant by the term “clean coal,” and can
coal ever be clean? Write a research paper defining “clean coal”
and exploring technologies that purport to make coal mining
"clean."
Select one:
A. An interview with an oil rig worker
b. An article about coal mining pollution
c. An encyclopedia article about the history of coal mining
d. A speech in which the president touts increasing clean coal jobs