Which chromophores are bound by plant cryptochromes?
Go with B — Flavin and pterin. Under cryptochrome, this is the standard explanation you’d use in class: it names the real driver or definition, while the rest are nearby but wrong. Not these: A) Chlorophyll and carotene; C) Biliverdin and phytochromobilin; D) Retinal and opsin. When two options sound similar, choose the one that matches the textbook definition most tightly.
Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.