Which Best Describes the Cost-Benefit Results of the First 20

Which best describes the cost-benefit results of the first 20 years of the Clean Air?

A) While costs have exceed benefits 2 to 1,benefits are expected to increase in the coming decades.
B) Because many of the benefits of clean air are intangible,it is not possible to make such comparisons.
C) Costs have been far greater than the benefits.
D) In 2010,alone,estimated benefits exceeded costs by 4 to 1.