Correct option : B Conjugated proteins are those which has a conjugated group or prosthetic group attached to it. Chromoproteins have pigmented prosthetic group attached to it. Phytochrome is a conjugated protein as it has chromophore as prosthetic group. It is a photodetector pigment in the plant. It is sensitive to the red and far-red region of the visible spectrum. It regulates the flowering. At 670 nm of light, it changes to Pfr and at 730 nm of light it changes to Pr. So, the correct answer is option B.
