Which preposition to use with c3

at Occurrences 1%

The stalwart with pearly teeth, lilac eyes and curly lashes is C3 at Lloyd's (Sir FRANCIS), and may be heard twice daily at the Frivolity singing, "My Goo-goo Girl from Honolulu" to entranced flappers; while the lad who has Fritzie D. Hun backed on the ropes, clinching for time, is usually gifted with bow legs, freckles, a dented proboscis and a coiffure after the manner of a wire-haired terrier.

to Occurrences 1%

That audacious eugenist, Nicky Chester, first Minister of Brains in the post-war period of official attempts to raise the nation from C3 to something nearer A1 on the intellectual plane, happens, because of his family history, to be uncertified for marriage.

Which preposition to use with  c3