9. Which of the following statements concern conditions that would not be considered a problem in implementing a uniform emissions standard? a. Firms that have similar marginal abatement cost curves but have different marginal damage curves because of their differing geographical locations. b. The cost of designing, organizing, implementing, and enforcing differing emission standards outweigh any possible inefficiency that may result from a "one size fits all" approach to environmental legislation, regulation, and enforcement of industry emissions. c. Firms with old abatement technology will generally co-exist alongside firms with newer abatement technology. d. A firm's marginal damages curve may vary with the time of year, reflecting that the firm's emissions may result in greater damages during the summer months than in the winter.