What wavelength out of red, green, blue and full spectrum would purple cabbage reflect, and what would it absorb?
I’ll assume you are asking about the purple parts of the cabbage leaves. A dark purple color like that will absorb a large percentage of most wavelengths. It will reflect some small fraction of the blue, very little to no green, and some red (probably a bit more than the blue). The same could be said for a full spectrum. It will absorb most of the energy in the green region of the spectrum, reflect some in the blue end, and a little bit more in the red end. Of course the best way to quantify this would be to measure a spectral reflectance curve using a spectrophotometer.
