The obvious answer is C. The other two are to colorful to fit the game setting. This isn't borderlands with cell shading.
B&W might actually fit the setting pretty well, though it would probably be better for Fallout than Wasteland.
I think it would be a bold move to go B&W, and selective color would really make things interesting (like in the movie Pleasantville)… Maybe have flags in color, red blood, fire/explosions in color, green radiation glow, etc.