Water containing toxic waste is flowing into a 10,000 L pond at a rate of 40 L per hour, and the pond is draining at the same rate. The concentration of toxic waste flowing in is 0.05 kg per liter. Init

a) 0.002 kg/L
b) 0.005 kg/L
c) 0.003 kg/L
d) 0.004 kg/L