CMYK is missing from the options in the Replace Color utility.

I teach a beginning class in Photoshop at a state university. In demonstrating the Replace Color utility, I use the CMYK percentages from the university communications toolbox because that formula is easiest to remember. One of my students (on a MAC, of course), does not have the CMYK option on the Result from the utility. It still appears on the Color Picker from the toolbar. If this is an intentional deletion, it’s a bad idea, replace it. If it’s not, how does she make this option appear?