The (C) series controls how much what what colors of pigment are found in the coat. Affects both the color, and the placement of the color.
As you read the following descriptions, notice that the further down the hierarchy you go, the lighter and lighter the color becomes. This is because more and more pigment is being removed from the coat.
C - "Full Color" Dominant over all the others. Normal amount of pigment over the whole animal. Examples include black, orange, chestnut, otter, tortoise (tort), and their blue, chocolate, and lilac counterparts.