A single rapid test to determine the pollu-tional status of river water is :

ANS:C - total organic solids

Answer C is correct since Carbonaceous Analyzer is used to measure the total organic solids (TOC) of a wastewater sample in just two minutes.

Whereas BOD is measured in 5 days at 20°C.

COD can be measured in just 3 hours involving a acidic oxidation with potassium dichromate.

Dissolved oxygen is the amount of oxygen in the dissolved state present in the wastewater.