In this paper we have investigated two related issues: (a) representability of a choice function: (b) characterization of a representable choice functions, namely the utilitarian choice function. Probably the most well-known representable choice function is the one due to Nash (1950), which is characterized by properties similar to those which characterize the utilitarian choice function, except that instead of shift invariance we have scale invariance for Nash's solution. Our proof of representability is simpler and easier to comprehend than most other proofs existing in the literature. Our characterization of the utilitarian choice function is both elegant and concise. The meaningfulness of the properties characterizing this solution, should enhance its appeal as a choice function.