Saturation

This choice will take the most saturated colors in your image and make sure they end up as the most saturated colors that are possible in CMYK mode. That might sound nice, but it doesn't take into account the brightness, color, and saturation differences between colors. That means that it is free to shift the colors in your image as long as saturated colors remain saturated, even if they don't end up looking anything like the color at which they started. That limits its usefulness to solid-colored graphics such as bar charts and business graphics where the relationship between colors isn't important and you just want to maintain vivid colors no matter what.