Backscratcher for me. I've had a couple of sets of full fenders, but I'm just not that nice to them. They wind up broken after two years, tops. Using the backscratcher means wetter, dirtier feet, but that's what boots are for. Easy to move it from one bike to another, also.

I'd guess a modified answer A would be my choice:

Full fenders with mudflaps really do keep road grit off me and the bike, but cost a lot, don't last long if you're hard on 'em and are difficult to move from one bike to another.