Your file must be in CMYK if you are having it printed. RGB is based on display colors (red, green, and blue light), whereas cmyk stands for pigments (cyan, magenta, yellow, and black). To make sure your art file is using the correct color separations, you will want to open up the Separations Preview under the Window menu. This will show you you a Separations Preview panel where you can turn on and off the color separations individually. If more than CMYK are in there, then it will be displayed, meaning it is a spot color.
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