Black radiator shroud, a paint I´ve only seen on pictures of the earlist models and only for american market. Europe had them red, blue and black.
Rectangular fluid reservoir (-78 had round), no spoke tabs (-78 had them), mono front brake, no thumbnail screen (came 1980). The winkers / indicators seem strange but AFAIK the picture is from a Honda Sales brochure. It "must" be a 1979 US standard model?? Typical American bars, too.
1979 CX500 Standard. (We didn't get the A, B, C designations.) It had the later style indicators, square master cylinder, and gold highlights on the trim. At least some had a locking fuel cap cover like the Deluxe. All else identical to the '78.
P.S. I don't recall the spoke tabs (rivet covers) missing on the '79, but I've only seen a few examples.