UVR8 lacks which component?
That points to B: Chromophore. Compared with the other options, Chromophore is the one that correctly describes the PSS-Sec-E-Sensory biology concept. The wrong ones are A) Dimer structure; C) Tryptophan residues; D) β-propeller fold. If you’re stuck, eliminate anything that contradicts a basic fact you already know for this topic.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.