For doctors, there is no equivalent to C) (I don't think you can really be a "freelance doctor" without any degree).
Well, of course it depends on what it is about being a doctor I value. If I want to help sick people become healthy, for example, there are lots of equivalents to C.
Admittedly, the most effective ones don't involve practicing medicine, which falls into the "go do something else" category. But even if I what I want is to help sick people become healthy by practicing medicine, there are still equivalents to C -- there are plenty of areas full of sick people who can be helped to become healthy through the practice of medicine without a degree.
There just isn't a lot of status or money in doing that.
Peter Thiel is offering another round of "20 under 20" Fellowships. The application deadline is December 31st. We know many of the current Thiel fellows here in the Bay Area, and it's a great opportunity. Here's the official letter from the Thiel Foundation: