How to get just 1 or 2 colors to appear in black&white picture. 10 POINTS!?

Question: How to get just 1 or 2 colors to appear in black&white picture!. 10 POINTS!!?

so if i start with a colored picture,
turn it black & white
how do i make it so that, say, just the greens and blues of the picture are in color!?

is there a way to do that without layering and erasing everything of that color!?

like pressing a certain button to get just those colors to show!?

muchhhh appreciated!. thanks! ?
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Best Answer - Chosen by Asker:

Not sure what program you are using but in Gimp Just desaturate each color that you dont want!. In Gimp go under colors/hue-saturation!. Then adjust the colors!. Dont make it b&w first!.Www@QuestionHome@Com