Assume that the BOD of a sample to be tested is about 200 mg/l and the DO is zero.The DO of dilution water to be used is known to be 8 mg/I. Which of the following ratios of dilution water wastewater sample would most logically be used in setting up a BOD bottle for incubation? (a) 20/1; (b) 50/1; (c) 100/1; (d) 500/1.