A bulk tanker truck carrying 5,000 gallon of methyl tertiary-butyl ether (MTBE), CASS#163-04-4, has collided with a bridge structure over a small river near a community. THE MTBE tank has ruptured, releasing an unknown amount of gasoline additive into the river about 1/4 mile upstream from the town's drinking water source intake. The following data apply to MTBE:

Oral RfD 0.005 mg/Kg*day
Inhalation RfD 0.143 mg/Kg*day
Manufacturer's suggested exposure limit 600 mg/m^3 (200 ppm)
Vapor pressure 25 °C 245 mm Hg
Density at 4 °C 0.741 g/cm^3

It is proposed to treat the towns water supply to remove mtbe to an acceptable concentration. Assume a 365 day exposure duration and complete absorption into the bod. The maximun mtbe concentration in the drinking water to proctet a 15 kg child population consuming 1.0L/day of water is most nearly:

a. 0.00075
b. 0.0075
c. 0,075
d. 0.75