The "C STICKER" was to be place on the automobile and represented those who were defined to have "essential activities". The follow page of the War Ration book list these activities.
Of course, official government or Red Cross business was first on the list. School teachers and school attendance were next. [4 or more in same vehicle.] Then came the mail delivery, newspaper, and "newsreel" all before the physician, surgeon, and veterinarian. The Public Health nurse was listed just before "Embalmer". The minister, priest or rabbi followed the embalmer! [seems like it should have been the other way around...:-)]
Are you on the list? No gas for you if not!