As I have said (ranted on) before, unfortunately the patent system has little to do with protecting the small, one man inventor and everything to do with protecting large corporations, despite its alleged reasons for its existence. However there are examples where it does work in this way - I reckon less than 0.1% of patents fall into this category though. I think you have to know how to work the system and it would also depend on the nature of the invention, the field of business, how easy it would be to understand and utilise and its likely overall value. a, b and c can all work but it wouldn't be an easy ride.
The conventional route would be 'a' but patent laws are not wholly international even if you shell out the small fortune needed to register your patent in every region you can think of that may have the ability to exploit it. You would have to be really sure it was watertight with no work-arounds and no damaging prior art that people could point to - it has to be completely original. You would also have to be sure that it could be used to make money. Having done all that, you could then either try to set up a company or, alternatively, pursuade an existing company to exploit the patent for a variety of potential personal rewards to be negotiated. It depends on how much hassle you want and how long you want to wait for a return. If you invent an anti gravity machine this may well be the best option - as long as the interests of the state (usually the military) don't prevent you from revealing it - I believe this is possible in the UK.
For most though patents are some variation of ideas that are not so revolutionary and most patents that are published can be challenged (certainly in electronics) and many claims proved invalid (it seems people register variations of the schmitt trigger every month). Even if the design is original you then have the choice of paying lawyers to defend it - and against a counter claim by (say) Motorola it would cost a lot, or selling the patent for much less than you may think it worth to a similar company. This is not easy without contacts and good negotiating skills.
Also patenting in one part of the world does not necessarily hold in other parts and some countries don't care anyway - international agreements or not.
Route 'c' is a good route if the market is likely to be short lived and not too expensive to set up a company to exploit the ideas involved. It may still need outside funding and manufacturing support though, so setting up from scratch is, for most people, not a viable option.
A bit depressing really. I suggest going for the anti-gravity device and let me know if you need a partner:-)