A single primary radar (skin paint) gives you bearing and distance, nothing else. If you observe multiple returns you can deduce heading and speed.
If you want altitude you need a second radar stations returns time synchronized to the 1st station., and observing multiple sweeps.
I'm not counting a tactical radar that has a very narrow beam width and a very narrow scan angle, and has almost no use for civil aviation.
BTW: who is the genius that decided mode A would be Code, and mode C would be Altitude?
