The correct option is (d) Sulphite oxidation method
To explain: The oxygen-transfer rate is determined by the oxidation of sodium sulphite solution. This technique does not require the measurement of dissolved oxygen concentrations.
As oxygen enters solution it is immediately consumed in the oxidation of sulphite, so that the sulphite oxidation rate is equivalent to the oxygen-transfer rate. Since the dissolved oxygen concentration, is zero then the kLa may then be calculated from the equation:
kLa = OTR / C*
where OTR is the oxygen transfer rate.
