Keep in mind a secondary source is "information written by someone who did not experience first-hand."
Thus the answer is A.
Are there multiple choices? if not id have to say because PLAIN has more a strategic plan to influence them
The correct answer is B.
The first two sentences are establishing characteristic shared by both petroleum and coal. The word "however" is used to contrast the similarities already presented with the differences that will be stated in the following sentences.
Answer: c, one is slightly less traveled
