A chlorinator is set to feed 40 pounds of chlorine in 24 hours to a flow rate of 0.85 million gallons per day. the chlorine, as measured by the chlorine residual test after 30 minutes of contact time, is 0.5 milligrams per liter (mg/l). find the chlorine demand in mg/L.
A. 5.6 mg/L
B. 6.1 mg/L
C. 6.6 mg/L
D. 5.1 mg/L