Which statement is true about BOD and COD in wastewater, and which responds faster to pollution?

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The key idea is what each test tells you about the pollution load and how fast you get results. BOD measures biodegradable organics—oxygen that microorganisms would use to biologically decompose organic matter in water over a set period (usually about five days). COD measures chemically oxidizable organics—oxygen required to oxidize organic matter (and some other substances) using a strong chemical oxidant in a matter of hours. Because the COD test relies on a rapid chemical reaction, it provides a quicker estimate of the pollutant load, including materials that microbes can’t readily break down, while BOD reflects only what microbes can actually consume over several days. The statement that best fits this is that BOD measures biodegradable organics, COD measures chemically oxidizable organics, and COD responds faster than BOD.