Sorry, but option A ain't going to cut it where really big bears live... in the rain and wind. I'll take option B every time and this is one of those cases where bigger is definitely better; if my finger doesn't fit down the bore, it ain't big enough (.450 or .500 Alaskan)!

I know several people that have been mauled though and every one of them will tell you that it just doesn't matter. You're not going to get it out in time to do anything with it anyway. Option C: curl up in a ball, protect your head, and hope for the best.