21. What utility function does NOT represent the preferences of an individual over soda (S) and ice (1), where the individual only enjoys ice-cold glasses of soda (or fractions of ice-cold glasses of soda). To make a proper ice-cold glass of soda, the soda and ice must be in a 1:3 ratio. For instance, 1.5 sodas and 4.5 ice cubes would make 1.5 glasses of ice-cold soda. (Assume S and I take positive values only.) A. U(S, I) =min(3S, I) B. U(S,I)=min(S. c. U(S, I) =(min(1.5S, - 2 D. A-C are all valid representations E. A-C contains no valid representations