According to paragraph 2, which of the following is true of the change of solid organic material into oil and gas? A. It is more likely to occur along the base of continental slopes than on the continental shelves. B. It only takes place in areas where the seafloor contains at least 8 percent organic matter. C. It is a process that can be reversed through chemical changes that occur after the oil and gas have formed. D. It involves a complicated series of chemical reactions.