> This must be more than an illusion because for instance right now I am writing about it so that "sense" is affecting my actions.

No, it could be that (c) is an illusion of the fact that you are doing the writing, which I guess is the result of enough (a). There is some scientific evidence that (c) is 'constructed' afterwards by (a) and (b). For example (c) looks to lag about half a second behind the actual sensed reality.