Both petroleum and coal are made up of complex carbon-based molecules, and both originated with living creatures of some kind. both are vital sources of energy for the modern world and both were formed by geologic processes over millions of years. however, petroleum was mainly formed from the remains of ocean-dwelling microorganisms. coal, on the other hand, originated from decayed vegetation in ancient swamps and bogs. in any case, it took millions of years for both coal and oil to be produced. this is the case because it took that much time for overlying sediments to produce the unimaginable heat and pressure that would one day allow us to harvest these energy resources. this passage uses a combination of comparison and contrast and a. chronological order. b. cause and effect. c. supporting details. d. examples and explanations.

What type of writing is demonstrated in this excerpt by general philip henry sheridan? at once i set about preparing for the examination which precedes admission to the military academy, studying zealously under the direction of mr. william clark; my old teachers, mcnanly and thorn, having disappeared from somerset and sought new fields of usefulness. the intervening months passed rapidly away, and i fear that i did not make much progress, yet i thought i should be able to pass the preliminary examination. that which was to follow worried me more and gave me many sleepless nights; but these would have been less in number, i fully believe, had it not been for one specification of my, outfit which the circular that accompanied my appointment demanded. this requirement was a pair of "monroe shoes." now, out in ohio, what "monroe shoes" were was a mystery—not a shoemaker in my section having so much as an inkling of the construction of the perplexing things, until finally my eldest brother brought an idea of them from baltimore, when it was found that they were a familiar pattern under another name. a. research essay b. persuasive essay c. biography d. memoir