Why does the professor think that it is inappropriate for certain wavelengths of light to be named "far-red"? A. Far-red wavelengths appear identical to red wavelengths to the human eye. B. Far-red wavelengths have the same effects on plants as red wavelengths do. C. Far-red wavelengths travel shorter distances than red wavelengths do. D. Far-red wavelengths are not perceived as red by the human eye.