You are being obtuse on purpose, just by seeing the cones in their eyes we can know what colors they can see. Also, the italics part agrees with what I said, yellow and blue are colors.So how are they going to tell you? Or do the dogs in your country communicate in your native language
Perhaps I should have been specific and suggested green
While we can't ask dogs to read an eye chart or pick out colors, behavioral tests suggest that dogs see in shades of yellow and blue and lack the ability to see the range of colors from green to red. In other words, dogs see the colors of the world as basically yellow, blue, and gray.