20. What quantity of foam concentrate shall be supplied on chemical tanker stipulated in IBC Code (International Code for the construction and equipment of ships carrying dangerous chemicals in bulk)? (A) At least 20 minutes of foam generation when using the highest of the solution rates. (B) At least 30 minutes of foam generation when using the highest of the solution rates. (C) At least 40 minutes of foam generation when using the highest of the solution rates. (D) At least 60 minutes of foam generation when using the highest of the solution rates.