Which of the following most logically completes the passage?

A recent government study links the high rates of respiratory ailments in Groverston to airborne pollutants released by the Woodco plywood manufacturing plant there. To address the problem the government imposed strict regulations on emissions which will go into effect in four years. Although Woodco plans to cut its emissions in half two years ahead of schedule, it is unlikely that the rate of respiratory ailments will decline before the regulations go into effect, since _______.

• Athe number of facilities capable of treating respiratory ailments is not likely to increase  
• Breducing emissions even further than planned would necessitate decreasing production at Woodco  
• Cit is difficult to make accurate, long-term predictions about emissions  
• Dnot all respiratory ailments are caused by airborne pollutants  
• Ethree new plywood manufacturing plants are about to go into production in Groverston