In a well-aerated and agitated microbial culture, the ‘supply’ of oxygen is equal to demand: C = instantaneous value of dissolved oxygen concentration T = specific oxygen uptake rate per unit weight of cells X = dry weight of the cells per unit volume Options: (A) (r X) / (C*- C) (B) (r) / X (C*- C) (C) (C”- C) / (r X) (D) (X) / r (C*- C)

Answer: (B) (r) / X (C*- C)
Explanation: In a well-aerated and agitated culture, the ‘supply’ of oxygen meeting the ‘demand’ is represented by the ratio of the specific oxygen uptake rate (r) to the product of the dry weight of cells (X) and the difference between the saturation concentration of oxygen (C*) and the instantaneous value of dissolved oxygen concentration (C).